Answer
The average rate of change is $3$ units.
Work Step by Step
RECALL:
The average rate of change of a function from $x=a$ to $x=b$, where $a \gt b$, is given by the formula:
$\text{average rate of change} = \dfrac{f(b) - f(a)}{b-a}$
Use the formula above to obtain:
$\text{average rate of change}$
$\\= \dfrac{f(b) - f(a)}{b-a}
\\=\dfrac{f(4)-f(0)}{4-0}
\\=\dfrac{(3\cdot 4 - 5) - (3 \cdot 0 - 5)}{4}
\\=\dfrac{7-(-5)}{4}
\\=\dfrac{7+5}{4}
\\=\dfrac{12}{4}
\\=3$
