Lesson 1, Topic 1
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Lesson 9 How to Subtract Fractions by Trading and Practice & Assessment

Raquel February 11, 2023

Raquel Werk is inviting you to a scheduled Zoom meeting.

Topic: Fractions Class with Raquel
Time: May 19, 2023 10:00 AM Pacific Time (US and Canada)

Join Zoom Meeting
https://us04web.zoom.us/j/79772586384?pwd=JFMCayg9aVa2ROUWnKMiBxztehVGba.1

Meeting ID: 797 7258 6384
Passcode: nB3VbM

In this lesson, we continue subtracting fractions, but this time it requires taking from the whole number to make the first fraction larger so that you can subtract the second fraction.

TIPS

  1. Find a common denominator (use LCM – Least Common Denominator).
  2. Make equivalent fractions.
  3. Subtract the numerators and whole numbers. IF THE NUMERATOR YOU ARE SUBTRACTING FROM IS TOO SMALL, TRADE A FRACTION FROM THE WHOLE NUMBER TO MAKE IT BIGGER. See the video or Guidebook p.24 for details.
  4. Use the same denominator.
  5. Reduce or simplify to get the fraction in the lowest terms.

Sample Assessment for Subtracting Fractions with Trading

To subtract 7 and 1/3 minus 1 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 a 4 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 7 and 4/12 minus 1 and 6/12. Now, when you subtract the numerators 6 (the subtrahend/second number) from 4 (the minuend/first number), you don’t have enough. In order to make the 4/12 bigger, you take 1 from the whole number, 7, and turn 1 into a fraction using the denominator of both fractions, which is twelve, and then add it to 4/12 to make it bigger. Now the problem becomes 6 and 16/12. Subtract the numerators and whole numbers to get 5 and 10/12. Finally, reduce that answer by dividing the numerator and denominator by 2 to get a final answer of 5 and 5/6.

ACTION STEP: Practice subtracting fractions on the worksheets from Unit 5 until you can complete one whole worksheet in less than 25 minutes with no more than 2 incorrect (8 must be correct).