The glass cups are 15.20 yuan each, and the ceramic cups are 2.9 yuan cheaper than the glass cups. How much is a glass cup and a ceramic cup?
玻璃杯每个15.20元，陶瓷杯每个比玻璃杯便宜2.9元，买一个玻璃杯和一个陶瓷杯共多少钱？
<gadget id="calculator">15.2 - 2.9</gadget>
<output>12.3</output>

<gadget id="calculator">12.3 + 15.2</gadget>
<output>27.5</output>

<result>27.5</result>