Xiaomi pays 135 yuan for a pair of sports shoes, 85 yuan for a football, and pays the salesperson 250 yuan. How much should the salesperson get her back?
小米买一双运动鞋要135元，一个足球85元，付给营业员250元，营业员应该找回她多少元．
<gadget id="calculator">135 + 85</gadget>
<output>220</output>

<gadget id="calculator">250 - 220</gadget>
<output>30</output>

<result>30</result>