Answer:
x² +3x -50 = 0
Step-by-step explanation:
The area expression you got in part (a) is ...
A = (x +8)(x -5) = x² +3x -40
If the area is to be 10, then x must satisfy the equation ...
10 = x² +3x -40
x² +3x -50 = 0 . . . . . . subtract 10 and put in standard form
