Xiaoli bought 3 water glasses, paid 50 yuan, and got back 2.3 yuan. What is the unit price of the water glasses?
小莉买了3个水杯，付了50元，找回2.3元，水杯的单价是多少．
<gadget id="calculator">50 - 2.3</gadget>
<output>47.7</output>

<gadget id="calculator">47.7 / 3</gadget>
<output>15.9</output>

<result>15.9</result>