U who took my charger

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

Mario has $14.35 left in his wallet. he spent $148.43 for tablecloths. then, he spent $92.05 for napkins. how much money did mario have in his wallet to start with?

Find the least common multiple of the expressions: 1. 3x^2, 6x - 18 2. 5x, 5x(x +2) 3. x^2 - 9, x + 3 4. x^2 - 3x - 10, x + 2 explain if possible