If there are 8 slices in a large pizza, how many slices will remain if Mary orders 2 large pizzas and eats 7 slices?
The number of total slices of pizza is 8 slices per pizza * 2 large pizzas = 
<gadget id="calculator">8*2</gadget>
<output>16</output>
16 slices.
If Mary eats 7 slices, then 16 - 7 = 
<gadget id="calculator">16-7</gadget>
<output>9</output>
9 remain.

<result>9</result>