2003 AMC 8 Problems/Problem 4
Problem
A group of children riding on bicycles and tricycles rode past Billy Bob's house. Billy Bob counted children and wheels. How many tricycles were there?
Solution
If all the children were riding bicycles, there would be wheels. Each tricycle adds an extra wheel and extra wheels are needed, so there are tricycles.
or
Setting up an equation, we have children and . Solving for the variables, we get, tricycles.