12. Your marks show the products that need to be formed:
x² -4x -5x +20
Simplifies to
x² -9x +20
14. Divide by the coefficient of x. Since it is positive, you do not need to reverse the inequality symbol.
x > 3.5
14. The diagram shows all numbers between -2 and +2, inclusive.
-2 ≤ x ≤ 2
15. Divide by the coefficient of c.
c = A/d