Let the price for hardcover books = x
Let the price for paperback book = y
According to the statement- Adam sold 4 hardcover books and ten paperbacks and earned $64
the equation becomes
4x + 10 y = 64................ (i)
According to statement Barb sold 5 hardcover books and 7 paperbacks for the same prices each and made $58.
The equation becomes
5x + 7 y = 58...............(ii)
But as it is mentioned that Barb sold the hardcover and paperback books the same price, this gives
5x = 7y............... (iii)
x = [tex]\frac{7y}{5}[/tex]
Now adding both equations (i) and (ii) we get
9x + 17y = 122
putting the value of x here we get
9[tex]\frac{7y}{5} +17y = 122[/tex]
[tex]\frac{63y}{5} +17y =122[/tex]
63y + 85y = 610
148y = 610
y = 4.121
now as x = [tex]\frac{7y}{5}[/tex]
x = [tex]\frac{7*4.121}{5}[/tex] =5.769
Now we get x = 5.769 and y = 4.121
Hence, the price of hardcover book is $5.769 and paperback book is $4.121