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?
The bike repairs cost $20 because 80 x .25 = 
<gadget id="calculator">80*.25</gadget>
<output>20</output>
20.
Call the amount he earns e. We know that e - 20 = 1/5e.
Therefore 5e - 100 = e.
Therefore, 4e = 100.
Therefore, e = 
<gadget id="calculator">25</gadget>
<output>25</output>
25.
Therefore, he sold 20 apples because 25 / 1.25 = 
<gadget id="calculator">25/1.25</gadget>
<output>20</output>
20.

<result>20</result>