Question

20% of your customers Call back within 72 hours Of their first call. Of those who call back, 10% call back again within 96 hours of their First call. Of the 140 customers you spoke with Yesterday, how many calls from those customers Will you receive in the next four days?

Answer 1

0.20 X 140 = 28
0.10 x 28 = 2.8 (You round it up to 3)
28+ 3 = 31

Answer 2

20% of 140 is 28, and 10% of 28 is 2.8 which I'm assuming you would round up to 3.
28+3=31. so you were called back 31 times after your 140 customers:)