1st column = price of books

2nd column = no. of books sold. = -1032*1st column+38440

3rd column = cost of books = 4.9*2nd column

4th column = profit = 3rd column - 2nd column*1st column.

(4.9*(-1032*x+38440))-(-1032*x+38440)*x

is the equation to the max profit. after putting 1,2,3,4 together.

after rearranging and simplify.

(4.9*(-1032*x+38440))-(-1032*x+38440)*x

=1032x^2-43496.8x+188356

then to find max. you differentiate the equation to

2064x-43496.8=0

to find x

2064x=43496.8

x= 21.07

hence the max profit = $21

please ask questions if you dont understand as i havent explain it fully.