Question

f is the function f(x) = 2x + 5 find f(3)

Answer 1

f(3) = 2(3) + 5 
f(x) = 6+5
f(x) = 11

Answer 2

First you input the x value in the place of x
f(3) = 2(3) + 5
Then mutiply it
f(3) = 6 + 5 
Which equals 11
f(3) = 11