Madelyn drove a race car in a race. She averaged 55 mph and began the race 0.5 hours ahead of the other drivers. The variable d represents Madelyn's distance driven, in miles. The variable t represents the number of hours since the other drivers began to race. Which equation can be used to determine the distance Madelyn drove t hours into the race?
a. d=55(t+0.5)
b. d=55(t−0.5)
c. d=55t−0.5
d. d = 55t + 0.5