Find a basis B (fancy B) of R^2 such that the B-matrix (fancy B) of the linear transformation

T(x) = [-5 -9

4 7]x (Where x is a vector) is B (regular B) = [1 1

0 1]

They give [-9 and [0 as an example of an answer. Just not sure how

6] 1] they get that answer.