f(9) is the x value, find where the line is in the y direction at x = 9
The line crosses y = 3 at x = 9
Answer:
f(9) = 3
The answer to -3-8+(-4) is -15
Use substitution.
2p + 3(2p) = 680
2p + 6p = 680
8p = 680
p = 85
Plug in.
x = 2p
x = 2(85)
x = 170
p = 85