Manual travel 2 hours non-stop to Mexico a total of 90 miles. He took a train part of the way, which averaged 60 mph, and then took a bus the remaining distance, which averaged 30mph. How long was Manuel on the train?

Time t=distance/speed. If T is the time on the train and D is the distance travelled by train, D=60T. The remaining distance by bus is 90-D. The remaining time is 2-T, so 90-D=30 (2-T). Therefore 90=60T+60-30T and 30T=30 so T=1 hour on the train.