SOLUTION: can you help me please.the cost of 20 books is $85.00.some of the books cost $8.00 each and the others cost $3.00 each.how many of each type were bought?

Question 190494: can you help me please.the cost of 20 books is $85.00.some of the books cost $8.00 each and the others cost $3.00 each.how many of each type were bought?
Answer by jonvaliente(64) (Show Source): You can put this solution on YOUR website!
Let x=no of $8-book
. y=no of $3-book
.
We know that there were 20 books, so:
(1)
.
Also, we know that the cost of all the books is $85, so:
(2)
.
Let's multiply (1) by 3 to get:

.
Let's subtract this new equation from (2) to get:

-
===============

.
Dividing both sides by 5 we get:

.
Now we know that there were 5 8-dollar books and 20-5=15 3-dollar books.
.
To check:
5*8+15*3=?85
40+45=?85
85=85
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