Explanation:
just plug in the numbers to the x values
if f(3) then ur equation would look like this f(3) = 4x - 5
then u solve it to get the answer.
3 = 4x - 5
+ 5 = 4x + 5
------------------ ---> add 5 on both sides
8 = 4x
now u just divide. 8 ÷ 4 = 2 so f(3) = 2