| x |  |  |  |  |
| f(x) | 21 | 18 | 15 | 12 |
The table above shows some values of x and their corresponding values 
for the linear function f. What is the x-intercept of the graph of 
in the xy-plane?
| x | | | | |
| f(x) | 21 | 18 | 15 | 12 |
The table above shows some values of x and their corresponding values for the linear function f. What is the x-intercept of the graph of in the xy-plane?