The whole class of Class 3 in the sixth grade subscribes to the two publications "Primary School Student Composition" and "Youth". If the number of subscribers is 2/3, if there are 6 people who subscribe to both publications, how many people are there in the class?
六年级3班全班订阅《小学生作文》和《少年》这两种刊物，订阅刊物的人数占全班总人数的90%，订阅《小学生作文》的占订阅人数的50%，订阅《少年》的占订阅人数的(2/3)，两种刊物都订阅的有6人，则全班共有多少人．
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(9/10) * (1/2)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(9/10) * (2/3)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(3/5) - (9/10)</gadget>
<output>-3/10 = around -0.3</output>

<gadget id="calculator">(9/20) + (-3/10)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">6 / (3/20)</gadget>
<output>40</output>

<result>40</result>