Question: Find the answer to this math problem: Mike needed a new pair of jeans.  When he got to the mall he saw that his favorite jeans were advertised 25% off.  The original price of the jeans was $40.  How much money will Mike have left over if he pays with a $50.00 bill?
Answer: 
The jeans cost $40 and are sale for 25% off so 40 * .25 = $10.00 discount
Take the original cost of the jeans and subtract the discount so 40-10 = $30.00
Mike pays with a $50 bill and the final cost of the jeans is $30 so 50-30 = $20.00 left