Question 1016510
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P=number of paperbacks; H=number of hardcover books
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P+H=86
P=86-H . Use this to substitute for P below.
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$5.95P+$19.75H=$939.50 . Substitute for P from above. 
$5.95(86-H)=$19.75H=$939.50
$511.70-$5.95H+$19.75H=$939.50
$13.80H=$427.80
H=31
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ANSWER 1: 31 hardcover books were sold.
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P=86-H=86-31=55
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ANSWER 2: 55 paperback books were sold.
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CHECK:
$5.95P+$19.75H=$939.50
$5.95(55)+$19.75(31)=$939.50
$327.25+$612.25=$939.50
$939.50=$939.50
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