Enter an equation that can be used to solve this problem, where x represents the number of hours that roberto had been traveling.

roberto left his parent's house at 11 a. m. traveling at an average rate of 30 mph. his parents left their house at 12 p. m. traveling at an average rate of 45 mph going the same way as roberto so that they could catch up to him. after how many hours will it take roberto's parents to catch up to him?

enter the amount of hours after roberto left that it will take roberto's parents to catch up to him (assume that they do not stop).
equation:

h:
i need the equation and the hours