On Children's Day, Grandpa Liu took his three grandchildren to the park to play. The children's tickets were half priced at 7.5 yuan each. How much did they spend on the tickets?
儿童节那天，刘爷爷带着3个孙子去公园玩，儿童门票半价为每张7.5元，他们买门票一共要花多少钱？
<gadget id="calculator">7.5 * 3</gadget>
<output>22.5</output>

<gadget id="calculator">7.5 * 2</gadget>
<output>15</output>

<gadget id="calculator">22.5 + 15</gadget>
<output>37.5</output>

<result>37.5</result>