#### Answer

(a) $d = 48t$
(b) See image for graph
(c) The slope of this line represents the constant speed at which Jason travelled.

#### Work Step by Step

(a) To express distance travelled as a function of time elapsed, we multiply speed with time to get distance, or:
$d = vt$
Where $v$ is speed. Rearranging the equation and inputting values from the problem gives:
$v = \frac{d}{t}$
$v = \frac{40}{50/60}$ (where 50/60 is the fraction of an hour it took to travel)
$v = 48$ mph
Inputting this value in the original equation gives:
$d = 48t$
(b) Graph a linear function with $m=48$ and $b=0$ by plotting two points and joining them.
(c) The slope represents the constant speed at which Jason travelled, as shown in the explanation for (a). It is a constant speed and not simply an average speed since it is stated explicitly in the question that it was constant.