What is the correct answer?

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

Which of these equations, when solved, gives a different value of x than the other three? a9.1 = -0.2x + 10 b10 = 9.1 + 0.2x c10 – 0.2x = 9.1 d9.1 – 10 = 0.2x

Jacks bank statement shows an account balance of -$25.50. which describes the magnitude, of size, of the debt in dollars