As pajama sets are made up of a top and a bottom, there are 4 pajama sets * 2 = <<4*2=8>>8 articles of clothing from Adam's donation.
In total, Adam is donating 4 pairs of pants + 4 jumpers + 8 pajama pieces + 20 t-shirts = <<4+4+8+20=36>>36 articles of clothing.
Together, the 3 friends donate a total of 36 articles of clothing per friend * 3 friends = <<36*3=108>>108 articles of clothing.
Adam changes his mind and takes back half, which means he is now actually donating 36 / 2 = <<36/2=18>>18 articles of clothing.
There is therefore now a total of 108 + 18 = <<108+18=126>>126 articles of clothing being donated.
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