John buys 20 hours of music a month.  The average length of a song is 3 minutes.  He buys each song for $.50.  How much does he pay for music a year?
He buys 20*60=
<gadget id="calculator">20*60</gadget>
<output>1_200</output>
1200 minutes of music a month.
So that is 1200/3=
<gadget id="calculator">1200/3</gadget>
<output>400</output>
400 songs.
That means he pays 400*.5=$
<gadget id="calculator">400*.5</gadget>
<output>200</output>
200 a month.
So it comes out to 200*12=$
<gadget id="calculator">200*12</gadget>
<output>2_400</output>
2400 a year.

<result>2_400</result>