Answer:
x=7
Explanation:
The function is:
f(x)=3x-21.
The zero(s) is/are any value(s) that make(s) the function equal(s) to zero.
This implies that, to find the zero(s), we equate the function to 0 and solve for x
This implies that:
3x-21=0
3x=21
Dividing through by 3, we obtain
x=7