How to add and subtract fractions

You need to find the common denominator.

In your question:

4 2/7 - 2 1/5

= 4/1 * 2/7 - 2/1 * 1/5

= 8/7 - 2/5 ⇒ There, the common denominator is 7 * 5 = 35

= (8*5) / (7*5) - (2*7) / (5*7)

= 40/35 - 14/35

= (40-14) / 35

= 26/35

You need to find the common denominator of all of the fraction and you also have to do whatever you did to the bottom to the top. So if you times the bottom by 2 you need to times the top by two. Then once you have that you can add and subtract!