bought 20 first stamps and 10 post card stamps for $17.10. she spent $70.00 on 80 1st class stamps and 50 post card stamps. Find cost of each stamps.

Question

A student  bought 20 first stamps and 10 post card stamps for $17.10.

Another day she spent $70.00 on 80 1st class stamps and 50 post card stamps.

Find the cost of each type of stamps.

Answer 1

Set up and solve a system of equations.
Let x represent the cost of 1st class stamps

Let y represent the cost of post card stamps

17.10 = 20x + 10y  ....  (1)

70.00 = 80x + 50y  ....  (2)

 

subtracting 4 of equation 1 from equation 2 you obtain the following:

 

1.6 = 10y

which gives y = .16

Therefore post card stamps cost $0.16

Plugging this back into either equation you get x = .775

Therefore the cost of 1st class stamps is $0.775