Answer:
9/20
Explanation:
After Bob eats 1/4 of the pie, he has 3/4 left. 2/5 of 3/4 is the same as (2/5)*(3/4) because "of" is used as multiplication in math. (2/5)*(3/4)=6/20, so he ate 6/20 of the pie. To get the answer, you need to solve 1-(1/4+6/20)=
1-(5/20+6/20)=20/20-11/20=9/20. I hope this helps and sorry if I made a mistake. :)