Xiao Ming bought 5 kg of apples for 16.5 yuan, and bought 7 kg of pears for 21.7 yuan. Which fruit is the cheapest? How much cheaper?
小明买5千克苹果用去16.5元，买7千克雪梨用去21.7元，哪种水果便宜？便宜多少？
<gadget id="calculator">16.5 / 5</gadget>
<output>3.3</output>

<gadget id="calculator">21.7 / 7</gadget>
<output>3.1</output>

<gadget id="calculator">3.3 - 3.1</gadget>
<output>0.2</output>

<result>0.2</result>