A factory decides to stop making cars and start making motorcycles instead. When it made cars, per month, it cost $100 for materials, they could make 4 cars, and they sold each car for $50. Now that they make motorcycles it costs $250 for materials, but they sell 8 of them for $50 each. How much more profit do they make per month selling motorcycles instead of cars?
They sold $200 worth of cars each month because 4 x 50 = 
<gadget id="calculator">4*50</gadget>
<output>200</output>
200.
They made $100 a month off cars because 200 - 100 = 
<gadget id="calculator">200-100</gadget>
<output>100</output>
100.
They sold $400 worth of motorcycles each month because 8 x 50 = 
<gadget id="calculator">8*50</gadget>
<output>400</output>
400.
They make $150 a month off motorcycles because 400 - 250 = 
<gadget id="calculator">400-250</gadget>
<output>150</output>
150.
They make $50 more a month off motorcycles than cars because 150 - 100 = 
<gadget id="calculator">150-100</gadget>
<output>50</output>
50.

<result>50</result>