I am trying to help my grandson with a fraction problem, Mary has 12 marbles 3/12 are yellow,2/12 are blue and the rest are green, I need to explain how many of them are green where he will understand

Answer 1

You can add up fraction of yellow and blue subtract from 1 to get green

1- ([2/12+ 3/12)

1- 5/12

(12-5)/12
= 7/12

Green is 7/12