The equation x2 - 1x - 90 = 0 has solutions {a, b}. What is a + b?

A) - 19

B) - 9

C) 1

D) 10

The answer would be 1

x² - x - 90 = 0

x² - 10x + 9x - 90 = 0

x (x - 10) + 9 (x - 10) = 0

x (x) - x (10) + 9 (x) - 9 (10) = 0

(x + 9) (x - 10) = 0

x + 9 = 0 or x - 10 = 0

- 9 - 9 + 10 + 10

x = - 9 or x = 10

{a, b} = {-9, 10}

a + b = - 9 + 10

a + b = 1

The answer is C.