The ratio of rates is; hence, the ratio of times is . It means that if the time going to the mountains is 3x hours, then the time returning is 5x hours. We are given that 5x - 3x = 3 hours; hence, 2x = 3, x= 3/2 hours and the time driving home is = = 7.5 hours = 7 hours and 30 minutes. ANSWER