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?
Algebra ->
Expressions-with-variables
-> 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?
Log On
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
