Solve for X: Combining Fractions 1/4x - 1/5x + 2/3x - 2/5x = 1

Fraction Operations with Multiple Terms

Solve for X:

14x15x+23x25x=1 \frac{1}{4}x-\frac{1}{5}x+\frac{2}{3}x-\frac{2}{5}x=1

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve
00:04 We want to isolate the unknown X
00:08 We'll multiply by the common denominator to eliminate fractions
00:22 We'll divide 60 by each appropriate fraction
00:44 We'll solve each multiplication separately
00:56 We'll collect like terms
01:01 We'll isolate the unknown X
01:12 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 for X:

14x15x+23x25x=1 \frac{1}{4}x-\frac{1}{5}x+\frac{2}{3}x-\frac{2}{5}x=1

2

Step-by-step solution

To solve the given equation 14x15x+23x25x=1 \frac{1}{4}x - \frac{1}{5}x + \frac{2}{3}x - \frac{2}{5}x = 1 , follow these steps:

Step 1: Find a common denominator for the fractions involved. The denominators are 4, 5, 3, and again 5. The least common multiple (LCM) of these numbers is 60.

Step 2: Rewrite each fraction with the common denominator of 60:

  • 14x=1560x\frac{1}{4}x = \frac{15}{60}x
  • 15x=1260x-\frac{1}{5}x = -\frac{12}{60}x
  • 23x=4060x\frac{2}{3}x = \frac{40}{60}x
  • 25x=2460x-\frac{2}{5}x = -\frac{24}{60}x

Step 3: Combine the fractions:

1560x1260x+4060x2460x\frac{15}{60}x - \frac{12}{60}x + \frac{40}{60}x - \frac{24}{60}x

This simplifies to:

1512+402460x=1960x\frac{15 - 12 + 40 - 24}{60}x = \frac{19}{60}x

Step 4: Set up the equation:

1960x=1\frac{19}{60}x = 1

Step 5: Solve for x x by isolating it on one side of the equation. Multiply both sides by the reciprocal of 1960\frac{19}{60}, which is 6019\frac{60}{19}:

x=1×6019x = 1 \times \frac{60}{19}

x=6019x = \frac{60}{19}

Therefore, the solution to the problem is x=6019=157 x = \frac{60}{19} = \frac{15}{7} after simplifying the fraction.

3

Final Answer

157 \frac{15}{7}

Key Points to Remember

Essential concepts to master this topic
  • Common Denominator: Find LCD of all denominators to combine fractions
  • Technique: LCD of 4, 5, 3, 5 is 60: 14=1560 \frac{1}{4} = \frac{15}{60}
  • Check: Substitute x=6019 x = \frac{60}{19} back: 19606019=1 \frac{19}{60} \cdot \frac{60}{19} = 1

Common Mistakes

Avoid these frequent errors
  • Adding or subtracting fractions without finding common denominator
    Don't try to combine 14x15x \frac{1}{4}x - \frac{1}{5}x directly without common denominators = nonsensical result! You can't add fractions with different denominators. Always find the LCD first, then convert all fractions before combining.

Practice Quiz

Test your knowledge with interactive questions

\( x+7=14 \)

\( x=\text{?} \)

FAQ

Everything you need to know about this question

Why can't I just work with the original fractions?

+

You need a common denominator to add or subtract fractions! Just like you can't add 14+15 \frac{1}{4} + \frac{1}{5} without converting to 520+420 \frac{5}{20} + \frac{4}{20} first.

How do I find the LCD of 4, 5, and 3?

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List multiples of each number until you find the smallest one they all share:
4: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60
5: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60
3: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60

The arithmetic looks complicated. Is there an easier way?

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Take your time with each step! Convert one fraction at a time: 14=1×154×15=1560 \frac{1}{4} = \frac{1 \times 15}{4 \times 15} = \frac{15}{60} . Then carefully add and subtract the numerators: 15 - 12 + 40 - 24 = 19.

Why is the final answer 15/7 instead of 60/19?

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There's an error in the explanation! The correct coefficient is 1960 \frac{19}{60} , so x=6019 x = \frac{60}{19} . This doesn't simplify to 157 \frac{15}{7} - that appears to be a mistake in the original solution.

How do I check if 60/19 is correct?

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Substitute back: 1960×6019=19×6060×19=1 \frac{19}{60} \times \frac{60}{19} = \frac{19 \times 60}{60 \times 19} = 1 ✓. The fractions cancel perfectly, confirming our answer!

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