Why is this wrong? im so confused

well if he bought them at 5 cedis each sold them at 7 cedis each then he would make a profit of 2 cedis of each book. if in total he made 150 cedis profit that means he sold 75 books. he lost 12 books at the start so that means he originally bought a total of 82 books.

step-by-step explanation:

if your equation is in the form ax2 + bx + c, you can find the maximum by using the equation:

max = c - (b2 / 4a).

the first step is to determine whether your equation gives a maximum or minimum.

-x2 + 4x - 2.     thats an example hope it