Question

Using only 32-cent and 20-cent stamps, Charlie put $3.36 postage on a package he sent to his sister,

He used twice as many 32-сent stamps as 20 cent stamps. Determine how many of each type of stamp
he used.

Answer 1

No. of 32 cent stamps = 8

and that of 20 cent stamps = 4

Explanation:

Let no. of 32 cent stamps used be x and the number of 20 cent stamps used be y.

We are given that total postage on a package put by Charlie by using only 32 and 20 cent stamps is equal to $3.36.

So, since 100 cents make one dollar, $3.36 = 336 cents.

So,

32x + 20y = 336

Also we are given that Charlie used twice as many 32 cent stamps as 20 cent stamps which can be written as,

x = 2y

Substituting this equation in previous equation we get

32
`*`2y + 20y = 336

=> 64y + 20y = 336

=> 84y = 336

=>y = 4

Putting the value of y in x = 2y we get x = 2*4 = 8

So, no. of 32 cent stamps = 8 and that of 20 cent stamps = 4

Answer 2

Charlie used 4 20-cent stamps and 8 32-cent stamps.

Explanation:

Let the number of 20 cents stamps be
`x`. Then, as per question, Chalie used twice as many 32-сent stamps as 20 cent stamps.

Therefore, number of 32-cent stamps is
`2x`.

Now, total cost of the stamps is $ 3.36 = 336 cents

Cost of 1 20-cent stamp is 20 cents. So, cost of
`x` 20-cent stamps is
`20x`. Similarly, cost of
`2x` 32-cent stamps is
`32(2x)=64x`

Total cost =
`20x+64x=84x`

As per question,

`84x=336\\x=(336)/(84)=4`

Number of 20-cent stamps =
`x = 4`

Number of 32-cent stamps =
`2x=2* 4=8`

So, Charlie used 4 20-cent stamps and 8 32-cent stamps.