The students go to the playground to play. There are 26 people who drive bumper cars, 30 people who ride on carousel, and 17 people who play with both kinds of toys. How many people are there who drive bumper cars and ride on merry-go-round?
同学们到游乐场去玩，开碰碰车的有26人，坐旋转木马的有30人，两种玩具都玩的有17人，开碰碰车和坐旋转木马的同学共有多少人．
<gadget id="calculator">30 - 17</gadget>
<output>13</output>

<gadget id="calculator">26 + 13</gadget>
<output>39</output>

<result>39</result>