Investigate the number of people who can play Chinese chess and international chess among 300 students in the sixth grade. It is found that 50 students can't do both. There are (2/15) students who can do both, and there are (4/5) students who can play Chinese chess. , How many students are there who can play chess?
在六年级300名学生中调查会下中国象棋和国际数棋的人数，发现50名同学两样都不会，有(2/15)的学生两样都会，有(4/5)的学生会下中国象棋，会下国际数棋的学生有多少名．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">300 * (4/5)</gadget>
<output>240</output>

<gadget id="calculator">300 - 50 - 240</gadget>
<output>10</output>

<gadget id="calculator">2 / 15</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">300 * (2/15)</gadget>
<output>40</output>

<gadget id="calculator">10 + 40</gadget>
<output>50</output>

<result>50</result>