Gail has some bills in her wallet which amount to $100. She has four $5 bills and three $20 bills, and the rest are $10 bills. How many $10 bills are in her wallet?
Four $5 bills amount to $5 x 4 = $
<gadget id="calculator">5*4</gadget>
<output>20</output>
20.
Three $20 bills amount to $20 x 3 = $
<gadget id="calculator">20*3</gadget>
<output>60</output>
60.
So Gail's $5 and $20 bills amount to $20 + $60 = $80.
Thus, her $10 bills amount to $100 - $80 = $20.
Therefore, she has $20/$10 = 
<gadget id="calculator">20/10</gadget>
<output>2</output>
2 $10 bills.

<result>2</result>