James went to the store to return a defective $45 tape recorder for a refund. At the same time, he bought some batteries for $3 per package. If he received $33 dollars of his refund, how many packages of batteries did he buy?

a.

4

c.

2

b.

11

d.

15

Answer is 4 packages:

n: number of packages of batteries

$45 = $3n + $33

$45 - $33 = $3n

$12 = $3n

$12/$3 = n

4 = n

He bought (a.) 4 packages of batteries. He returned the defective tape recorder for a store credit of $45 dollars. We know that he received $33 in refund, so the amount of money he spent on batteries is his store credit minus the refund ($45-$33), which is $12. Each package of batteries costs $3, so the amount of packages he bought can be found by dividing the money he spent by the cost per package, or $12/$3, which is equal to 4 packages.