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?

2 Answers
Tessalsifi
Mar 5, 2018

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.

Tony B
Mar 5, 2018

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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Check

#10xx45=450 cents#
#5xx1=5cents#

Total is 455 cents = $4.55

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