Xiaohong, Xiaohong's mother, Xiaoming, and Xiaoming's mother played together in the park. They bought four tickets and spent a total of 11 yuan. Adult tickets cost 4 yuan each, and how much do children's tickets cost? (solution by equation)
小红、小红的妈妈、小明、小明的妈妈四个人一块公园玩，买了四张门票共花了11元，成人票每张4元，儿童票每张多少钱？(用方程解)
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">11 - 8</gadget>
<output>3</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<result>3/2 = around 1.5</result>