Answer:
3. 5 miles per hour.
Explanation:
the slope is always the ratio
(y coordinate difference / x circumstances difference).
the y coordinates represent miles, the x coordinates hours.
so, the slope represents miles/hours.
how many ?
we need to pick 2 points in the graph. i recommend to use points with integer coordinates, as they are the easiest to recognize.
we have e.g. (0, 0) and (1, 5)
x changes by +1 (from 0 to 1).
y changes by +5 (from 0 to 5).
so the slope is +5/+1 = 5/1 miles/hour = 5 mph