Brief Explanation

There are two young people in the mountain. A young guy keeps walking. A girl often tries to stop him but he never stop. Why does he keep walking? It's because he is a character in mathematical problems. Like below " Q: Ken left home at 75m/min and his brother chased him in his bike at 250m/min one hour later. What time did his brother catch up with him?" So, for junior high school students, let’s keep on going your successes!