Question

Andy, David and Tim altogether have 180 stamps. Andy has 20 fewer than David, and Tim has 80% of the sum of Andy's and David's stamps.How many stamps does each of them have?

Answer 1

andy has 40

david has 60

tim has 80

Answer 2

Explanation:

Alright, lets get started.

Let Andy have A stamps.

Let David have D stamps.

Let Tim have T stamps.

Andy, David and Tim altogether have 180 stamps, means

`A+D+T=180....................... equation 1`

Andy has 20 fewer than David, means

`A+20=D...............................equation 2`

Tim has 80% of the sum of Andy's and David's stamps, means

`(A+D)*0.8=T........................equation 3`

Putting the value of D as A+20 in equation 1 and 3

`A+A+20+T=180`

`2A+T=160`........................equation 5

`(A+A+20)0.8=T`

`(2A+20)0.8=T`

`1.6A+16=T` ....... equation 6

Plugging the value of T in equation 5

`2A+1.6A+16=160`

`3.6A=144`

`A=40`

`D = 40+20 = 60`

`T=1.6*40+16`

`T=64+16=80`

It means Andy has 40 stamps.

It means David has 60 stamps.

It means Tim has 80 stamps.

Hope it will help :)