A bus travels at a constant speed. The following table shows the distance the bus travels (in kilometers) over a period of time (in hours):

distance (d) 42 ,252 ,378
time (t) 0.5, 3, 4.5

a. Use complete sentences to describe the relationship represented in the table.
b. Write an equation using variables that represents the relationship shown in the table.
c. Use your equation to find how far the bus travels in 6 hours.