Answer:
Hardcover books cost 35 $ and paperback books cost 16$
Explanation:
Lets call h = hardcover books , and p = paperback books
* 2 copies of the hardcover book "h" and 3 copies of the paperback book cost 118
2h + 3p = 118 (equation 1)
* 3 hardcover books and 2 paperback books cost 137
3h+2p=137 (equation 2)
we have two equations, lets multiply as following
3 ×(2h + 3p = 118)
(-2) ×(3h + 2p = 137)
6h + 9p = 354
-6h - 4p =-274
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0h + 5p = 80 then p=80/5, p=16
from equation 1, if p=40
2h + 3 × (16) = 118
2h + 48 = 118
2h = 118 - 48
2h = 7
h=35