Answer:
z = 5
Step-by-step explanation:
x^2 + x - 20 = 0
Two numbers that multiply to get 20 are 5 and 4
(x + 5)(x - 4) = 0
Now we can check this equation:
x * x = x^2
x * -4 = -4x
5 * x = 5x
5 * -4 = -20
x^2 - 4x + 5x - 20 = 0
x^2 + x - 20 = 0
The solutions to this equation are 5 and -4, but since z is more than 0, z is 5
