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

Answer:

Step-by-step 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 :)