Solve: Adding Fractions 3/5 + 2/7 Step by Step

Fraction Addition with Unlike Denominators

35+27= \frac{3}{5}+\frac{2}{7}=

❤️ Continue Your Math Journey!

We have hundreds of course questions with personalized recommendations + Account 100% premium

Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve
00:03 We want to find the least common denominator
00:06 Multiply each fraction by the other denominator to find the common denominator
00:09 Remember to multiply both numerator and denominator
00:27 Calculate the multiplications
00:36 Add under the common denominator
00:41 Calculate the numerator
00:45 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

35+27= \frac{3}{5}+\frac{2}{7}=

2

Step-by-step solution

To solve the given problem, we will follow these steps:

  • Step 1: Determine a common denominator for the fractions.
  • Step 2: Convert each fraction to have the common denominator.
  • Step 3: Add the numerators and keep the common denominator.
  • Step 4: Simplify the resulting fraction if possible.

Let's proceed with each step:

Step 1: Determine a common denominator.
The denominators of the fractions are 5 and 7. The least common multiple (LCM) of 5 and 7 is 35. Thus, the common denominator is 35.

Step 2: Convert each fraction to have the common denominator of 35.
Convert 35\frac{3}{5} to a fraction with a denominator of 35: 35=3×75×7=2135 \frac{3}{5} = \frac{3 \times 7}{5 \times 7} = \frac{21}{35} .
Convert 27\frac{2}{7} to a fraction with a denominator of 35: 27=2×57×5=1035 \frac{2}{7} = \frac{2 \times 5}{7 \times 5} = \frac{10}{35} .

Step 3: Add the numerators and use the common denominator.
Now add the fractions: 2135+1035=21+1035=3135 \frac{21}{35} + \frac{10}{35} = \frac{21+10}{35} = \frac{31}{35} .

Step 4: Simplify the result.
The fraction 3135\frac{31}{35} is already in its simplest form since 31 and 35 have no common factors other than 1.

Therefore, the solution to the problem is 3135 \frac{31}{35} .

3

Final Answer

3135 \frac{31}{35}

Key Points to Remember

Essential concepts to master this topic
  • Rule: Find least common multiple of denominators for common base
  • Technique: Convert 35 \frac{3}{5} to 2135 \frac{21}{35} by multiplying by 77 \frac{7}{7}
  • Check: Verify 2135+1035=3135 \frac{21}{35} + \frac{10}{35} = \frac{31}{35} in simplest form ✓

Common Mistakes

Avoid these frequent errors
  • Adding numerators and denominators separately
    Don't add 3+2=5 and 5+7=12 to get 512 \frac{5}{12} = completely wrong answer! This ignores that fractions represent parts of different-sized wholes. Always find a common denominator first, then add only the numerators.

Practice Quiz

Test your knowledge with interactive questions

Complete the following exercise:

\( \frac{3}{4}:\frac{5}{6}=\text{?} \)

FAQ

Everything you need to know about this question

Why can't I just add 3+2 and 5+7 to get 5/12?

+

Because 35 \frac{3}{5} means "3 parts out of 5" while 27 \frac{2}{7} means "2 parts out of 7". These are different-sized parts! You need to make the parts the same size first by finding a common denominator.

How do I find the least common multiple of 5 and 7?

+

Since 5 and 7 are both prime numbers, they have no common factors except 1. So their LCM is simply 5 × 7 = 35. For other numbers, list multiples or use prime factorization.

Do I always need to simplify my final answer?

+

Yes, always check! In this case, 3135 \frac{31}{35} can't be simplified because 31 is prime and doesn't divide 35. But always verify by finding the GCD of numerator and denominator.

What if the denominators have common factors?

+

Great question! If denominators share factors, use the LCM method instead of just multiplying them together. For example, LCM of 6 and 9 is 18, not 54, because they share the factor 3.

Can I convert to decimals instead of finding common denominators?

+

You could, but you'll often get messy decimals and might lose precision. Plus, many math problems require exact fraction answers. Learning the common denominator method gives you more accurate results!

Why is 31/35 already in simplest form?

+

Because 31 is a prime number and doesn't divide evenly into 35 (35 = 5 × 7). Since 31, 5, and 7 share no common factors except 1, the fraction cannot be reduced further.

🌟 Unlock Your Math Potential

Get unlimited access to all 18 Operations with Fractions questions, detailed video solutions, and personalized progress tracking.

📹

Unlimited Video Solutions

Step-by-step explanations for every problem

📊

Progress Analytics

Track your mastery across all topics

🚫

Ad-Free Learning

Focus on math without distractions

No credit card required • Cancel anytime

More Questions

Click on any question to see the complete solution with step-by-step explanations