Answer:
Step-by-step explanation:
Let H be the number of harcover, and S the number of softcover books.
We know that:
H+S=36
and $8*(H) + $2*(S) = $144
Rearrange the first: H = 36 - S
Use this definition of H in the second equestion:
$8*(H) + $2*(S) = $144
$8*(36-S) + $2*(S) = $144
$288 - 8S + 2S = $144
-6S = -144
S = 24
This means H = 36 - S is:
H = 36 - 24
H = 12
"You" purchased 24 softcover and 12 hardcover books.
Check the results: 24*2 + 12*8 = 48 + 96 = $144 It
works.