Answer
$f(x) = -2x + 3$
Work Step by Step
f(x) = ax + b
a is the slope.
Given that the rate of change is -2 and the initial value is 3, we know that a = -2, and b (the y-intercept) is 3 (since the initial value is at x=0)
Thus $f(x) = -2x + 3$