Pears cost 1.8 yuan per kilogram. If you buy X kilograms for 40 yuan, how much yuan should you get back?
梨每千克1.8元，用40元买X千克应找回多少元．
<gadget id="calculator">40 - 1.8</gadget>
<output>38.2</output>

<result>38.2</result>