The glass cups are 13.80 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13.80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">13.8 - 2.9</gadget>
<output>10.9</output>

<gadget id="calculator">10.9 + 13.8</gadget>
<output>24.7</output>

<result>24.7</result>