The milk is 35.5 yuan per box. Teacher Li bought 5 boxes of this milk and paid 200 yuan. How much should I get back?
牛奶每箱35.5元，李老师买5箱这样的牛奶，付出200元，应该找回多少元？
<gadget id="calculator">35.5 * 5</gadget>
<output>177.5</output>

<gadget id="calculator">200 - 177.5</gadget>
<output>22.5</output>

<result>22.5</result>