The formula which relates distance, speed, and time is:
d = rt, where d is the distance traveled, r is the rate of travel or speed, and t is the time traveled.
Since we're given that the car travels at a constant speed of 40 mi./hr. for a time t = 45 min., then we can use the distance-speed-time formula to find the distance d that the car will travel as follows:
d = rt
= (40 mi./hr.)(45 min.)
= (40 mi./hr.)(45 min.)(1)
= (40 mi./hr.)(45 min.)(1 hr./60 min.)
= (40 mi./hr.)(45/60 hr.)
= (40 mi./hr.)(3/4 hr.)
= (40)(3/4) mi.
= (10)(3) mi.
= 30 mi. is the distance a car traveling at a constant speed of 40 mi./hr. can travel in 45 min.
