George was selling some of his old toys on the internet. He managed to sell 3 little cars and a set of Legos. In total, he earned $45. How much did the Legos set cost, if one little car was sold for $5?
George sold 3 cars, so he earned 3 cars * $5/car = $
<gadget id="calculator">3*5</gadget>
<output>15</output>
15 from them.
The lego set cost was then $45 - $15 = $
<gadget id="calculator">45-15</gadget>
<output>30</output>
30.

<result>30</result>