Answer:
f(x) = -4x + 80
Explanation:
You are given two points,
(5, 60) and (10, 40)
in order to get the equation, let's use the form slope-intercept form
m = (y1 - y2) / (x1 - x2)
m = (60 - 40) / (5 - 10)
m = 20/-5
m = -4
Get the x intercept
y = mx + b
60 = (-4)(5) + b
b = 60+20
b = 80
so the equation is
y = -4x + 80
f(x) = -4x + 80