f(x)=9-2x
--------------------
f(x)=25
9-2x=25
-9 -9
-2x=16
/-2 /-2
x = -8
---------------------
f(x)=-41
9-2x=-41
-9 -9
-2x=-50
/-2 /-2
x = 25
----------------------
f(x)=17
9-2x=17
-9 -9
-2x=8
/-2 /-2
x = -4
-----------------------
f(x)=-8
9-2x=-8
-9 -9
-2x=-17
/-2 /-2
x = -17/2