Solve Fraction Addition: 3/5 + 2/15 Step-by-Step

Fraction Addition with Common Denominators

Solve the following exercise:

35+215= \frac{3}{5}+\frac{2}{15}=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve
00:03 Multiply the fraction by 3 to find the common denominator
00:07 Make sure to multiply both numerator and denominator
00:17 Calculate the products
00:27 Add with the common denominator
00:32 Calculate the numerator
00:37 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

Solve the following exercise:

35+215= \frac{3}{5}+\frac{2}{15}=

2

Step-by-step solution

Let's try to find the lowest common denominator between 5 and 15

To find the lowest common denominator, we need to find a number that is divisible by both 5 and 15

In this case, the common denominator is 15

Now we'll multiply each fraction by the appropriate number to reach the denominator 15

We'll multiply the first fraction by 3

We'll multiply the second fraction by 1

3×35×3+2×115×1=915+215 \frac{3\times3}{5\times3}+\frac{2\times1}{15\times1}=\frac{9}{15}+\frac{2}{15}

Now we'll combine and get:

9+215=1115 \frac{9+2}{15}=\frac{11}{15}

3

Final Answer

1115 \frac{11}{15}

Key Points to Remember

Essential concepts to master this topic
  • Rule: Find lowest common denominator before adding fractions together
  • Technique: Convert 35 \frac{3}{5} to 915 \frac{9}{15} by multiplying by 33 \frac{3}{3}
  • Check: Verify 915+215=1115 \frac{9}{15} + \frac{2}{15} = \frac{11}{15} cannot be simplified further ✓

Common Mistakes

Avoid these frequent errors
  • Adding numerators and denominators separately
    Don't add 35+215 \frac{3}{5} + \frac{2}{15} as 520 \frac{5}{20} ! This treats fractions like whole numbers and gives completely wrong results. Always find the common denominator first, then add only the numerators.

Practice Quiz

Test your knowledge with interactive questions

Without calculating, determine whether the quotient in the division exercise is less than 1 or not:

\( 5:6= \)

FAQ

Everything you need to know about this question

Why can't I just add 3 + 2 and 5 + 15?

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Because fractions represent parts of a whole! Adding 35+215 \frac{3}{5} + \frac{2}{15} as 520 \frac{5}{20} is like adding 3 apples and 2 oranges to get 5 appleranges - it doesn't make mathematical sense!

How do I find the lowest common denominator?

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Look for the smallest number that both denominators divide into evenly. Since 15 ÷ 5 = 3 and 15 ÷ 15 = 1, the LCD of 5 and 15 is simply 15!

What if the LCD isn't one of my denominators?

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Then you'll need to convert both fractions! For example, with 14+16 \frac{1}{4} + \frac{1}{6} , the LCD is 12, so you'd convert both to 312+212 \frac{3}{12} + \frac{2}{12} .

Do I need to simplify my final answer?

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Always check if you can simplify! In this case, 1115 \frac{11}{15} cannot be reduced because 11 and 15 share no common factors other than 1.

What if I get a mixed number in my answer?

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If your numerator is larger than your denominator, convert to a mixed number! For example, 1715=1215 \frac{17}{15} = 1\frac{2}{15} . Both forms are correct.

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