Answer
$5$ dollars
Work Step by Step
Make a system of equations out of this:
s is for softcover books, and h is for hardcover books.
The question says that you buy 4 hardcover books and 2 softcover books for 24 dollars
$4h + 2s = 24$
Buying 3 hardcover and 3 softcover costs 21 dollars
$3h + 3s = 21$
Now we have a system. Let's solve by graphing. Below is a graph attached, where the solution is noted (h,s)
The price of hardcover books is $5$ dollars
