Xiaoli goes to the post office to send things, and the postage is 1.6 yuan and 12.2 yuan respectively. Xiaohong gave her aunt 15 yuan, how much should she get back?
小丽去邮局寄东西，邮费分别是1.6元和12.2元．小红给阿姨15元，应该找回多少元．
<gadget id="calculator">1.6 + 12.2</gadget>
<output>13.8</output>

<gadget id="calculator">15 - 13.8</gadget>
<output>1.2</output>

<result>1.2</result>