Out of the 150 students, 100% - 60% = 40% are boys.
So, there are 150 x 40/100 = <<150*40/100=60>>60 boys.
Out of the 60 boys, 60 x 1/3 = <<60*1/3=20>>20 joined varsity clubs.
Therefore, 60 - 20 = <<60-20=40>>40 boys did not join varsity clubs.
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