can someone help me I am not understandng how to do this;

Function k(x) = x+18
Find k(0)
k(x) = 6x
k(-2)

k(5)
k(-2)
<P>indicated outputs
2
<P>F(x) = 4x - 5x

k(O) means find value of the function when x is O..so substitute x with O=> 0+18=18