Question

Ron used a combination of 45 cent stamps and 1 cent stamps to mail a package. He used 15 stamps in all. If the total cost for postage was $4.55, how many 1 cent stamps did he use?

Answer 1

5

Explanation:

Let's say `x` is the number of 45s, and `y` is the number of 1s. We have :
`x+y=15` ( number of stamps )
And `45x+y=455` ( total cost )
Thus :
`45x+y-x-y=455-15`
`44x=440`
Thus `x=10`
Take again the first equation :
`x+y=15`
`10+y=15`
`y=5`
He used 5 1c stamps.

Answer 2

There are 10 stamps at 45 cents
There are 15-10=5 stamps at 1 cent

Explanation:

Let the count of 45 cent stamps be `x`
Then the count of 1 cent stamps is `15-x`

So for total cost we have

`[45x+1(15-x)]cents=$4.55`

but there are 100 cents in 1 dollar so we change the above to

`([45x+1(15-x)])/100=4.55`

Multiply both sides by 100

`45x+15-x=455`

`44x=440`

`x=440/44`

`x=10`

There are 10 stamps at 45 cents
There are 15-10=5 stamps at 1 cent
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Check

`10xx45=450 cents`
`5xx1=5cents`

Total is 455 cents = $4.55