There will be $1000 x 3/10 = $<<1000*3/10=300>>300 worth of money that will be changed into $50 bills.
Uncle Bradley will have $300/$50 = <<300/50=6>>6 pieces of $50 bills.
He will change $1000 - $300 = $<<1000-300=700>>700 worth of money into $100 bills.
So there will be $700/$100 = <<700/100=7>>7 pieces of $100 bills.
Thus, there will be a total of 6 + 7 = <<6+7=13>>13 pieces of $50 and $100 bills in all.
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