Question

In a post-office, stamps of three different denominations of ` 7, ` 8, ` 10 are available. The exact amount for which one cannot buy stamps is (a) 19 (b) 20 (c) 23 (d) 29 explanation

Answer 1

Answer:

(a)19

Step-by-step explanation:

Rs.29= 3(Rs. 7 stamp)+ 1(Rs.8 stamp)

Rs.23= 1(Rs. 7 stamp) +2(Rs. 8 stamp)

Rs.20= 2(Rs.10 stamp)

So for Rs.19 one cannot buy any stamps.

Answer 2

Answer:

19

Step-by-step explanation:

Given In a post-office, stamps of three different denominations of ` 7, ` 8, ` 10 are available. The exact amount for which one cannot buy stamps is

We have 23 is possible by 8 + 8 + 7

              20 is possible by 10 + 10

              29 is possible by 7 + 7 + 7 + 8

 here only 19 is not possible for three different denominations.