Betty is saving money for a new wallet which costs $100. Betty has only half of the money she needs. Her parents decided to give her $15 for that purpose, and her grandparents twice as much as her parents. How much more money does Betty need to buy the wallet?
In the beginning, Betty has only 100 / 2 = $
<gadget id="calculator">100/2</gadget>
<output>50</output>
50.
Betty's grandparents gave her 15 * 2 = $
<gadget id="calculator">15*2</gadget>
<output>30</output>
30.
This means, Betty needs 100 - 50 - 30 - 15 = $
<gadget id="calculator">100-50-30-15</gadget>
<output>5</output>
5 more.

<result>5</result>