A bottle of milk is 1.3 yuan. My mother bought me 5 bottles and paid 10 yuan. How much should I get back?
牛奶每瓶1.3元，妈妈给我买了5瓶，付了10元钱，应找回多少元？
<gadget id="calculator">1.3 * 5</gadget>
<output>6.5</output>

<gadget id="calculator">10 - 6.5</gadget>
<output>3.5</output>

<result>3.5</result>