Two customers went to a post office. first customer paid $12 for 14 and 5 envelopes the second paid 24.80 for 10 postcards and 15 envelopes. what is cost of each envelope?

Each envelope is $1.42

Step-by-step explanation:

Let, the cost of postcards = x and the cost of envelopes = y, in dollars.

It is given that,

First customer paid $12 for 14 postcards and 5 envelopes.

This gives, 14x + 5y = 12.

Second customer paid $24.8 for 10 postcards and 15 envelopes.

This gives, 10x + 15y = 24.8

We get the system of equations,

14x + 5y = 12

10x + 15y = 24.8

We multiply 1st equation by 3. This gives us the equations,

42x + 15y = 36

10x + 15y = 24.8

Subtracting both equations, we get,

32x = 11.2

i.e.

i.e. x = 0.35

Which gives,

10 × 0.35 + 15y = 24.8

i.e. 15y = 24.8 - 3.5

i.e. 15y = 21.3

i.e.

i.e. y = 1.42

Hence, the cost of each postcard is $0.35 and each envelope is $1.42.