Leo has to write a 400-word story for his literature class. 10 words fit on each line of his notebook and 20 lines fit on each page. Lucas has filled one and a half pages. How many words does he have left to write?
Half a page is 20 / 2 =
<gadget id="calculator">20/2</gadget>
<output>10</output>
10 lines.
In total, he has written 20 + 10 = 
<gadget id="calculator">20+10</gadget>
<output>30</output>
30 lines.
The 30 lines written are 30 * 10 = 
<gadget id="calculator">30*10</gadget>
<output>300</output>
300 words.
Lucas has 400 - 300 = 
<gadget id="calculator">400-300</gadget>
<output>100</output>
100 words left to write.

<result>100</result>