Solve Mixed Number Subtraction: 3⅜ - 1¾

Mixed Number Subtraction with Different Denominators

328134= 3\frac{2}{8}-1\frac{3}{4}=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve
00:03 The formula for converting a mixed number to a fraction
00:12 We will use this formula in our exercise and convert to fractions
00:32 Divide the fraction by 2 to get a common denominator of 4
00:45 Subtract from the common denominator
00:58 Now convert back to a mixed number
01:02 Break down 6 into 4 plus 2
01:07 Break down into whole number and remainder
01:12 Convert from improper fraction to whole number
01:19 Reduce the fraction as much as possible
01:24 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

328134= 3\frac{2}{8}-1\frac{3}{4}=

2

Step-by-step solution

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

  • Step 1: Convert 1341\frac{3}{4} to a fraction with a denominator of 8.
  • Step 2: Subtract the whole numbers and fractions separately.
  • Step 3: Simplify the resulting fraction and combine it with the whole number part.

Now, let's work through each step:

Step 1: Convert 1341\frac{3}{4} to a fraction with a denominator of 8.
Since 34=68 \frac{3}{4} = \frac{6}{8} (by multiplying numerator and denominator by 2), we have:
134=1+68=88+68=1481\frac{3}{4} = 1 + \frac{6}{8} = \frac{8}{8} + \frac{6}{8} = \frac{14}{8}.

Step 2: Subtract the whole numbers and fractions separately.
Original problem: 328134=2681483\frac{2}{8} - 1\frac{3}{4} = \frac{26}{8} - \frac{14}{8}.

Subtract the fractions:
268148=128\frac{26}{8} - \frac{14}{8} = \frac{12}{8}.

Step 3: Simplify the resulting fraction and combine it with the whole number part.
128=32\frac{12}{8} = \frac{3}{2}.

Therefore, after subtracting and simplifying, we find that:

Therefore, the solution to the problem is 112 1\frac{1}{2} .

3

Final Answer

112 1\frac{1}{2}

Key Points to Remember

Essential concepts to master this topic
  • Common Denominators: Convert fractions to same denominator before subtracting
  • Technique: Convert 34 \frac{3}{4} to 68 \frac{6}{8} by multiplying by 2
  • Check: 112+134=314=328 1\frac{1}{2} + 1\frac{3}{4} = 3\frac{1}{4} = 3\frac{2}{8}

Common Mistakes

Avoid these frequent errors
  • Subtracting fractions without common denominators
    Don't subtract 2834 \frac{2}{8} - \frac{3}{4} directly = wrong answer like 14 \frac{-1}{4} ! Different denominators mean you're subtracting different-sized pieces. Always convert to the same denominator first, then subtract numerators.

Practice Quiz

Test your knowledge with interactive questions

\( 5\frac{2}{5}+2\frac{1}{5}= \)

FAQ

Everything you need to know about this question

Why can't I just subtract 2/8 - 3/4 directly?

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Because different denominators represent different-sized pieces! It's like trying to subtract 2 slices of pizza cut into 8 pieces from 3 slices cut into 4 pieces - you need to make the pieces the same size first.

How do I know which denominator to use?

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Use the Least Common Multiple (LCM) of the denominators. For 8 and 4, the LCM is 8 since 8 is already a multiple of 4. Convert 34 \frac{3}{4} to 68 \frac{6}{8} .

What if I need to borrow from the whole number?

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Sometimes you'll need to borrow! If the first fraction is smaller than the second, borrow 1 from the whole number and add it as an improper fraction to make subtraction possible.

Should I convert mixed numbers to improper fractions?

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Yes! Converting to improper fractions often makes subtraction easier. 328=268 3\frac{2}{8} = \frac{26}{8} and 134=148 1\frac{3}{4} = \frac{14}{8} , then subtract normally.

How do I simplify my final answer?

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Always reduce fractions to lowest terms! 128=32=112 \frac{12}{8} = \frac{3}{2} = 1\frac{1}{2} . Divide both numerator and denominator by their greatest common factor.

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