Answer:
40 Rs 2 coins equal to Rs 80.and this amounts 140— 80= Rs60.if i exchange one Rs 2 by one Rs 5 balance amount decreases by Rs3.For exhausting Rs 60 i shall have to exchange 60/3=20 Rs 2 coins.Thus 20 Rs 5 coin shallb there.ans.
Explanation:
answer not mine but hopefully it helps