Mr. Li buys 8 volleyballs, and each volleyball is a yuan. If you pay 150 yuan to the salesperson, how much should you get back?
李老师买8个排球，每一个排球a元，付150元给营业员应找回多少元．
<gadget id="calculator">150 - 8</gadget>
<output>142</output>

<result>142</result>