A kilogram of pears costs 3 yuan, and a kilogram of grapes costs 6 yuan. Buy 12kg of pears and 15kg of grapes, pay 150 yuan, how much will you get back?
梨3元钱一千克，葡萄6元钱一千克．买12kg梨和15kg葡萄，付150元，找回多少元？
<gadget id="calculator">3 * 12</gadget>
<output>36</output>

<gadget id="calculator">6 * 15</gadget>
<output>90</output>

<gadget id="calculator">36 + 90</gadget>
<output>126</output>

<gadget id="calculator">150 - 126</gadget>
<output>24</output>

<result>24</result>