Lesson 1, Topic 1
In Progress

Lesson 8 How to Subtract Fractions and Practice & Assessment

Raquel February 11, 2023

In this lesson, I will explain how to subtract fractions without trading.


  1. Find a common denominator (use LCM – Least Common Denominator).
  2. Make equivalent fractions.
  3. Subtract the numerators and whole numbers. Use the same denominator.
  4. Reduce or simplify to get the fraction in the lowest terms. If the final answer is an improper answer, be sure to explain in the assessment how to simplify the answer (Lesson 5). If it’s a proper fraction that needs to be reduced, be sure to explain in the assessment how to reduce the answer (Lesson 5). If the answer doesn’t need to be reduced or simplified, then state in your assessment, “That is the final answer because it doesn’t need to be reduced or simplified.”

Sample Assessment for Subtracting Fractions

To subtract 6 and 2/3 minus 3 and 2/4, you have to find the common denominator first. The common denominator of 3 and 4 is 12 because when you say the multiples of 3, you only get to the fourth one and when you say the multiples of 4, you get to the third one. Then, use the common denominator 12 to find a new numerator of the first and second fraction. The first numerator becomes an 8 because you multiply it by 4. The second numerator becomes a 6 because you multiply it by 3. The new fractions to be subtracted are 6 and 8/12 minus 3 and 6/12. Now, when you subtract the numerators 6 (the subtrahend/second number) from 10 (the minuend/first number) and the whole numbers 3 (the subtrahend/second number) from 6 (the minuend/first number), you get 3 and 2/12. To finalize the problem, simplify the answer by dividing the numerator and the denominator by 2 to get 3 and 1/6.

ACTION STEP: Practice subtracting fractions on the worksheets from Unit 5 until you can complete one whole worksheet in less than 20 minutes with no more than 2 incorrect (8 must be correct).