The y-intercept of f(x) = 5x - 45 would be -45, as that is what is represented in the equation. The way to find the x-intercept would be to solve the equation when f(x) = 0.
0 = 5x - 45
+ 45 + 45
45 = 5x
/5 /5
9 = x
And there we have it.
The intercepts of f(x) = 5x - 45 are as follows:
y-intercept = -45
x-intercept = 9
Hope that helped =)