SOLUTION: Jim recently purchased 120 stamps for $33.90. If the stamps were a combintation of .23 cent postcard stamps and .37 cent first class stamps, how many of each type of stamp were bou

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Question 161166: Jim recently purchased 120 stamps for $33.90. If the stamps were a combintation of .23 cent postcard stamps and .37 cent first class stamps, how many of each type of stamp were bought?
Found 2 solutions by nerdybill, amalm06:
Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
.
Let x = number of .23 stamps
then because Jim purchased a total of 120 stamps
120-x = number of .37 stamps
.
We also know that he spent a total of $33.90 therefore:
.23x + .37(120-x) = 33.90
.23x + 44.4 - .37x = 33.90
44.4 - .14x = 33.90
44.4 = .14x + 33.90
10.5 = .14x
75 = x (number of .23 stamps purchased)
.
.37 stamps:
120-x = 120-75 = 45 (number of .37 stamps purchased)

Answer by amalm06(224) About Me  (Show Source):
You can put this solution on YOUR website!
If Jim paid $33.90 for 120 stamps, then he paid 0.2825 for 1 stamp
Using the method of alligation,
0.2825-0.23=0.0525
0.37-0.2825=0.0875
Then P/F=0.0875/0.0525
E.g. for every 0.14 stamps, 0.0875 are postcard stamps
Then for 120 stamps, P=(0.0875/0.14)(120)=75 (Answer)
First class stamps=120-75=45 (Answer)