PreAlgebra
posted by Ola .
Courtnytravels south on her bicycle riding 8 miles per hour. One hour later, her friend Horacio starts riding his bicycle from the same location. If he travels south at 10 miles per hour, how long will it take him to catch Courtney?

Let x = hours
8x = 10(x1)
Solve for x. 
Sorry, you are PREalgebra, so you may not know how to solve for x.
8x = 10x  10
Subtract 10x from both sides.
2x = 10
Divide both sides by 2.
x = 5 
Evidently you haven't mastered preAlgebra since your answer is WRONG. It takes him 4 hours to catch her. While she does ride for 5 hours, it only takes him 4 to catch her.

Don't worry I had trouble with this to. If you think about if she is going 8 miles per hour and he is going 10 miles per hour. He is shaving o 20 minutes of her time every hour. She tables 16 miles in 2 hours he will travel 16 miles in 1 hour 40 minutes she travels 4 hours in 32 miles he travels 4 hours in 40 miles It will take 4 hours for him to catch up with her because he is going faster by two miles an hour. 2,4,6,8 in 4 hours he will make up for 8 miles.