Given f(x)= (4 + 5)(2 + d), determine the axis of symmetry in terms of d

18 + 9d = y is just a horizontal line line.....f(x) should have an 'x' in it.....

Oops sorry, I wrote it wrong.

This is the right question

Given f(x)= (4x+5)(2x+d), determine the axis of symmetry in terms of d.