Zhang Lan bought two books, one "Man Tianxia" for 9.86 yuan, and the other "Story King" was 1.58 yuan less than "Man Tianxia". Zhang Lan gave the salesperson 20 yuan, how much should I get back?
张兰同学买了两本书，一本《漫天下》9.86元，另一本《故事大王》比《漫天下》少1.58元，张兰同学给售货员20元钱，应找回多少元？
<gadget id="calculator">9.86 - 1.58</gadget>
<output>8.28</output>

<gadget id="calculator">20 - 9.86 - 8.28</gadget>
<output>1.86</output>

<result>1.86</result>