Reginald is selling apples. He sells each apple for $1.25. He plans to use his profits to help repair his bike. His bike cost $80 and the repairs cost 25% of what his bike cost. After the repairs are paid for, 1/5 of the money he'd earned remains. How many apples did he sell? Give me reasons, before answering the question
The bike repairs cost $20 because 80 x .25 = 20. Call the amount he earns e. We know that e - 20 = 1 / 5e. Therefore 5e - 100 = e. Therefore, 4e = 100. Therefore, e = 25. Therefore, he sold 20 apples because 25 / 1.25 = 20. So the final answer is 20.