He is washing 10 ounces of shirts because 2 x 5 = <<2*5=10>>10
He is washing 6 ounces of socks because 3 x 2 = <<3*2=6>>6
He is already washing 34 ounces of clothes because 10 + 10 + 8 + 6 = <<10+10+8+6=34>>34
He can wash 16 more ounces because 50 - 34 = <<50-34=16>>16
He can wash 4 pairs of underwear because 16 / 4 = <<16/4=4>>4
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