Jiajia bought a book for 6.55 yuan, bought a pen for 13.2 yuan, and paid the salesperson 20 yuan. How much should I get back?
佳佳买一本书用去6.55元，买一支钢笔用去13.2元，付给售货员20元，应找回多少元？
<gadget id="calculator">6.55 + 13.2</gadget>
<output>19.75</output>

<gadget id="calculator">20 - 19.75</gadget>
<output>0.25</output>

<result>0.25</result>