Out of the 150 students, 60% are girls and the rest are boys. Only 1/3 of the boys joined varsity clubs. How many of the boys did not join varsity clubs?
Out of the 150 students, 100% - 60% = 40% are boys.
So, there are 150 x 40/100 = 
<gadget id="calculator">150*40/100</gadget>
<output>60</output>
60 boys.
Out of the 60 boys, 60 x 1/3 = 
<gadget id="calculator">60*1/3</gadget>
<output>20</output>
20 joined varsity clubs.
Therefore, 60 - 20 = 
<gadget id="calculator">60-20</gadget>
<output>40</output>
40 boys did not join varsity clubs.

<result>40</result>