Question

I need a step by step explanation of how to do this problem mentally and quickly:
7 3/4- 1 2/7 - 3/2

Answer 1

first make all the denominators the same
7 3/4 =31/7 = 62/14
1 2/7 = 9/7 = 18/14
3/2 = 21/14
62-18-21=23
so the answer is 23/14 or 1 9/14