Answer:
It will take him 24 days to have Rs 60 in hand.
Explanation:
A man earns Rs 20 on first day and spends Rs 15 on next day. He again earns rs 20 on third day and spends Rs 15 on fourth day. It means that in 2 days, the man saves Rs 5, in 4 days, he saves 5 + 5 = Rs 10. On the sixth day,he would be having 5+5+5 = Rs15 and on the eighth day, he would be having 5+5+5+5 = Rs 20
If he continues to save in this way, the number if days it will take him to save Rs 60 would be
(60×2)/5 = 24