Math Problem Solver

Alden works in the city and lives in the suburbs with Nikka. Every afternoon, Alden gets on a train that arrives at the suburban station at five in the afternoon. Nikka leaves the house before five and drives at a constant speed to arrive at the train station at exactly 5 PM to pick up Alden. The route that Nikka drives never changes. One Tuesday morning, this routine is interrupted because there is a power failure at work. Alden gets to leave early and catches a train that arrives at the suburban station at 4 PM. Instead of calling Nikka to ask for an earlier pickup, Alden decides to have a little exercise. He begins walking home along the route that Nikka drives, knowing that eventually, Nikka will intercept Alden, and then will make a U-turn. This is indeed, what happens, and Alden ends up arriving at home 10 minutes earlier than on a typical day. Assuming that Alden's walking speed is constant, the U-turn takes no time, and that Nikka's driving speed is constant, how many minutes did Alden walk?