Please help!! my brain is blank I can't think ;^;

Let the closed interval [a , b] be the domain of function f. the domain of f(x - 3) is given by (a) the open interval (a , b) (b) the closed interval [a , b] (c) the closed interval [a - 3 , b - 3] (d) the closed interval [a + 3 , b + 3]

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

Which statements about these triangles is true