What is a zero of the function f(x) = 5x-20

The zero of the function can be found by solving f(x)=0
Solution to f(x)=5x-20
To find the zero of the function f(x)=5x-20
Let        f(x) = 0
       5x - 20 = 0
Using Addition Property of Equality, add 20 to both sides of the equation
       5x -20 + 20 = 0 + 20
                      5x = 20
Using multiplication Property of Equality, multiply both sides with 1/5
             5x (1/5) = 20 (1/5)
                        x = 4

Therefore the zero of the function f(x) = 5x -20 is {4}