Li Ming brought 20 yuan, bought a story book for 5.2 yuan, and bought a technology book for 13.5 yuan. How much money is left?
李明带20元钱，买一本故事书5.2元，一本科技书13.5元，还剩多少元？
<gadget id="calculator">5.2 + 13.5</gadget>
<output>18.7</output>

<gadget id="calculator">20 - 18.7</gadget>
<output>1.3</output>

<result>1.3</result>