There are several things this could mean from the way you put it.
f= -2+45(f-3) f=-2+4(5)(f-3) f=-2+4(5f)-3 And several others.
f=-2+45f-135 f=-2+20f-60 f=-2+20f-3
-44f=-137 -19f=-62 -19f=-5
f=3.113636 f=3.263157 f=0.263157
I hope this helps.
