vinoo7 wrote:

John purchased some shirts and trousers for $600. He paid $100 less for the shirts than he did for the trousers. If he bought 5 shirts and the cost of a shirt is $20 less than that of a trouser, how many trousers did he buy?

A) 4

B) 5

C) 6

D) 7

E) 8

Follow posting guidelines (link in my signatures), do make sure to put the correct topic title and OA. Also, do not forget to mention the source of the question.As for the question,

Let a,b be the number of shirts and trousers while S,T be the price of each shirt and each trouser respectively.

Thus, setting up the equations:

1) a*S+b*T = 600

2) a=5

3) -a*S+b*T = 100

4) T-S =20

4 distinct equations for 4 variables ---> solve the system to get, b=5.

From equations 1) + 3), 2b*T=700 ---> b*T=350 ---> a*S = 350-100=250 ---> as a=5 ---> S=50 $ per shirt

From 4), T= 50+20=70$ , hence b*T=350 ---> b = 350/70=5 trousers.

B is thus the correct answer.