What is G (f) = 3k (2) - 22 k=4 I can't get it

Solution k = {-1, - 5}

G (f) is just a variable, and that's what confuses most people. if you wanted to, the equation could still be the same and be written as:

x = 3k (2) - 22; k=4

But, to get the answer, you substitute k as 4, shown below:

x = 3 (4) (2) - 22

Next you multiply:

x = 12 (2) - 22

Then multiply 12 by 2:

x = 24 - 22

Then subtract and the answer will be 2