Peter has 20 books. He has read 40% of them. His brother has read 10% of them. How many more of these books has Peter read than his brother?
Peter has read 8 of these books because 20 x .4 = 
<gadget id="calculator">20*.4</gadget>
<output>8</output>
8.
His brother has read 2 of these books because 20 x .1 = 
<gadget id="calculator">20*.1</gadget>
<output>2</output>
2.
Peter has read 6 more books than his brother because 8 - 2 = 
<gadget id="calculator">6</gadget>
<output>6</output>
6.

<result>6</result>