Mom and Dad took Xiaoling and Xiaoling to go to the park. Tickets are 5 yuan per ticket for adults and 2.5 yuan per ticket for children. How much do they spend on tickets?
爸爸、妈妈带着小玲和小玲两同学去逛公园，门票成人5元/张，儿童2.5元/张，那他们买门票一共用多少钱？
<gadget id="calculator">2 * 5</gadget>
<output>10</output>

<gadget id="calculator">3 * 2.5</gadget>
<output>7.5</output>

<gadget id="calculator">10 + 7.5</gadget>
<output>17.5</output>

<result>17.5</result>