Frank wants to buy a new lamp for his bedroom. The cost of the cheapest lamp is $20, and the most expensive in the store is 3 times more expensive. How much money would Frank have remaining, if he currently has $90, and he buys the most expensive lamp available?
The most expensive lamp cost 20 * 3 = $
<gadget id="calculator">20*3</gadget>
<output>60</output>
60.
So if Frank would pay for that lamp, he would leave himself with 90 - 60 = $
<gadget id="calculator">90-60</gadget>
<output>30</output>
30.

<result>30</result>