Question

Grady rides his bike 60% faster than his little brother Noah. If Grady rides 12 miles further than Noah in two hours, how fast in miles per hour does Noah ride?

Answer 1

Let Noah's speed be v mph. Grady's speed is 1.6v. In 2 hours the distance difference is (1.6v − v)·2 = 0.6v·2 = 1.2v, which equals 12.
So 1.2v = 12, hence v = 10 mph.