Question

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?

Answer 1

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