If this seems too easy, then just let it slide a while..
If you were to ride a bike around a quarter-mile track once at an average speed of 10mph, what must your average speed be during a second lap, to make your average speed over both laps equal to 20mph?
If you were to ride a bike around a quarter-mile track once at an average speed of 10mph, what must your average speed be during a second lap, to make your average speed over both laps equal to 20mph?