Hey there!!
We have:
... f(x) = -12x + 7
... g(x) = 4x - 9
Now, we will have to find f(x) = g(x)
... f(x) = g(x)
... -12x + 7 = 4x - 9
... 9 + 7 = 4x + 12x
... 16 = 16x
... x = 16/16
... x = 1
Hence, the value of 'x' is 1.
Hope this helps!
Happy Thanksgiving! :)