A car travels 200 miles in the same time that a train travels 300 miles. The speed of the train is 20 miles per hour more than the speed of the car. Which equation could be used to determine the speed of the car, r, in miles per hour?

The equation is

time = distance/rate

and the train is going 300 miles

the car is going 200 miles

the train goes 20 miles faster than the car

fitting the numbers into the equation

200/r=300 / (r+20)

cross multiply

200/r = 300 / (r+20)

200 (r+20) = 300r

distributive property

4000+200r=300r

subtract 200r from both sides to add like terms

4000=100r

divide 100 from each side to get r by itself

40 = rate of car

60 = rate of train