David and Dasha went to the carnival, where there are 9 rides.  Each ride costs 2 ride tickets at $2 per ticket.  You can also buy a ride bracelet for $30 which gives you 9 rides.  If David buys a ride bracelet and Dasha buys tickets, and they ride all 9 rides, how much money does David save?
Each ride cost 2 x $2 = $
<gadget id="calculator">2*2</gadget>
<output>4</output>
4.
All 9 rides cost $4 x 9 = $
<gadget id="calculator">4*9</gadget>
<output>36</output>
36.
By bathing the ride bracelet, David saves $36 - $30 = $
<gadget id="calculator">36-30</gadget>
<output>6</output>
6.

<result>6</result>