2 good old story problems

Hey I am doing a graded homework and would like some help figuring out these story problems. I think I might have the right answer for the first one but I have no clue on the second one.

Mixture Problem: Billy likes to mix two cereals for breakfast. He wants to reduce his sugar intake without having to completely give-up Sugar-O's, his favorite cereal. Sugar-O's contain 20% sugar, while Health-Nut contains 5% sugar. How much of each cereal does he need in order to have a 25 g of a mixture that is 10% sugar?

Travel Time: You just got your license, so you are excited to drive on of the family cars on a driving family vacation. You are so excited that while your mom, who is driving the other car, travels at an average speed of 55 mph, you drive at an average speed of 68 mph. If you start out from home at the same time, and drive the same route, how much time will elapse before you are 15 miles ahead of your mom?