Answer
$f(x)=-x+3\ (0 \leq x \leq 3)$
$f(x)=2x-6\ (3 \lt x \leq 5)$
Work Step by Step
From 0 to 3 on the x-axis, the line has a slope of -1 and a y-intercept of 3, so we have:
$y=-x+3$
From 3 to 5 on the x-axis, the line has a slope of 2 and a y-intercept of -6 (if we extend the line down), so we have:
$y=2x-6$
Thus the function f(x) consists of:
$f(x)=-x+3\ (0 \leq x \leq 3)$
$f(x)=2x-6\ (3 \lt x \leq 5)$