Mom goes to the fruit market and buys 4 kilograms of apples and 3 kilograms of pears. The apples are 5 yuan per kilogram, and the pears are 4 yuan per kilogram. Mom gave 50 yuan. How much should I get back?
妈妈去水果市场买了4千克苹果和3千克梨，苹果每千克5元，梨每千克4元，妈妈给了50元，应找回多少元？
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">50 - 20 - 12</gadget>
<output>18</output>

<result>18</result>