Answer
(a) The slope is 0.8, and the y-intercept is (0,-6)
(b) The average rate of change is 0.8
(c) See the graph and intercepts below.
(d) The function is increasing since the slope is positive.
Work Step by Step
The function is in the form of y=mx+b.
$m$ is the slope of the function and, also, the average rate of change (in linear functions slope and the average rate of change are the same).
$b$ is the y-intercept.
To find the x-intercept(s), we set f(x) to 0 and solve for x:
$0=\frac{4}{5}x-6$
$\frac{4}{5}x=6$
$x=6\cdot\frac{5}{4}$
$x=7.5$
A linear function increases when its slope is positive, it decreases when its slope is negative, and it's constant when its slope is zero.