Joe's pizzeria has an amazing promotion. If you buy any regular large pizza you can get the next 3 medium pizzas for $5 each. What are your total savings if the regular medium pizza price is $18 and you take full advantage of the promotion?
If one medium pizza costs $18 and with the promotion I can buy one for $5, then I'm saving $18-$5 = $
<gadget id="calculator">18-5</gadget>
<output>13</output>
13 on each medium pizza.
If I take full advantage of the promotion, that means I bought all 3 medium pizzas, therefore I saved a total of 3*$13 = $
<gadget id="calculator">3*13</gadget>
<output>39</output>
39 in total.

<result>39</result>