John writes 20 pages a day.  How long will it take him to write 3 books that are 400 pages each?
He wants to write 3*400=
<gadget id="calculator">3*400</gadget>
<output>1_200</output>
1200 pages.
So it will take him 1200/20=
<gadget id="calculator">1200/20</gadget>
<output>60</output>
60 days.

<result>60</result>