Simplify 2/5x + 4/3y + 7/9x + 3/4y: Combining Like Terms with Fractions

Combining Like Terms with Fractional Coefficients

25x+43y+79x+34y=? \frac{2}{5}x+\frac{4}{3}y+\frac{7}{9}x+\frac{3}{4}y=\text{?}

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Simplify the expression
00:05 Mark the appropriate variables
00:12 Use the commutative law and arrange the appropriate variables together
00:32 Multiply each fraction by the denominator of the second fraction to find the common denominator
00:35 Make sure to multiply both numerator and denominator
01:11 Collect terms, add with common denominator
01:22 Calculate the sums
01:33 Convert to mixed fraction
01:42 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

25x+43y+79x+34y=? \frac{2}{5}x+\frac{4}{3}y+\frac{7}{9}x+\frac{3}{4}y=\text{?}

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the given expression and separate like terms.
  • Step 2: Find a common denominator for terms with same variables.
  • Step 3: Add the fractions for each group of like terms.
  • Step 4: Simplify the expression to find the final result.

Now, let's work through each step:
Step 1: The expression is 25x+43y+79x+34y\frac{2}{5}x + \frac{4}{3}y + \frac{7}{9}x + \frac{3}{4}y. Group like terms together:
(25x+79x)+(43y+34y)(\frac{2}{5}x + \frac{7}{9}x) + (\frac{4}{3}y + \frac{3}{4}y).

Step 2: For (25x+79x)(\frac{2}{5}x + \frac{7}{9}x), find a common denominator for the fractions 2/52/5 and 7/97/9, which is 45.
Convert 25\frac{2}{5} to 1845\frac{18}{45} and 79\frac{7}{9} to 3545\frac{35}{45}.

Step 3: Add the fractions for xx:
1845x+3545x=5345x\frac{18}{45}x + \frac{35}{45}x = \frac{53}{45}x.

For (43y+34y)(\frac{4}{3}y + \frac{3}{4}y), find a common denominator, which is 12.
Convert 43\frac{4}{3} to 1612\frac{16}{12} and 34\frac{3}{4} to 912\frac{9}{12}.

Add the fractions for yy:
1612y+912y=2512y\frac{16}{12}y + \frac{9}{12}y = \frac{25}{12}y.

Step 4: Combine results to express the simplified form:
5345x+2512y\frac{53}{45}x + \frac{25}{12}y.

As mixed numbers, the solution becomes:
1845x+2112y1\frac{8}{45}x + 2\frac{1}{12}y.

Therefore, the solution to the problem is 1845x+2112y1\frac{8}{45}x + 2\frac{1}{12}y.

3

Final Answer

1845x+2112y 1\frac{8}{45}x+2\frac{1}{12}y

Key Points to Remember

Essential concepts to master this topic
  • Like Terms: Variables with same letter can be combined together
  • Common Denominators: Convert 25 \frac{2}{5} to 1845 \frac{18}{45} when LCD is 45
  • Check: Count terms before and after: 4 terms become 2 terms ✓

Common Mistakes

Avoid these frequent errors
  • Adding coefficients without finding common denominators
    Don't add 25+79=914 \frac{2}{5} + \frac{7}{9} = \frac{9}{14} ! This ignores different denominators and gives completely wrong results. Always find the LCD first, then convert both fractions before adding.

Practice Quiz

Test your knowledge with interactive questions

Are the expressions the same or not?

\( 3+3+3+3 \)

\( 3\times4 \)

FAQ

Everything you need to know about this question

Why can't I just add the numerators and denominators separately?

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Because fractions represent parts of different wholes! Adding 25+79 \frac{2}{5} + \frac{7}{9} means adding 2 fifths plus 7 ninths - you need a common denominator to combine them properly.

How do I find the LCD of 5 and 9?

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List multiples of each number: 5, 10, 15, 20, 25, 30, 35, 40, 45... and 9, 18, 27, 36, 45... The first number that appears in both lists is your LCD!

What if the fractions don't simplify nicely?

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That's okay! Sometimes answers like 5345 \frac{53}{45} can't be simplified further. You can leave it as an improper fraction or convert to a mixed number like 1845 1\frac{8}{45} .

Do I have to convert to mixed numbers?

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Not necessarily! Both 5345x \frac{53}{45}x and 1845x 1\frac{8}{45}x are correct. Mixed numbers are often easier to understand, but improper fractions work fine too.

Can I combine the x and y terms together?

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No! Terms with different variables are not like terms. You cannot combine 5345x \frac{53}{45}x and 2512y \frac{25}{12}y - they must stay separate in your final answer.

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