There are 36 students in Class 1 of the sixth grade, among them (2/3) like to dance, (3/4) like to sing, no one likes neither dancing nor singing. How many people like dancing and singing?
六年级一班有36人，其中(2/3)喜欢跳舞，(3/4)喜欢唱歌，没有人既不喜欢跳舞又不喜欢唱歌．既喜欢跳舞又喜欢唱歌的有多少人．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(3/4) - 1</gadget>
<output>-1/4 = around -0.25</output>

<gadget id="calculator">(2/3) + (-1/4)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">36 * (5/12)</gadget>
<output>15</output>

<result>15</result>