Pete’s wallet contains 2 * 20 = <<2*20=40>>40 dollars
The money in Pete’s pockets is 4 * 10 = <<4*10=40>>40 dollars
In total Pete has 40 + 40 = <<40+40=80>>80 dollars
He owes 90 dollars on the bike and therefore needs 90 - 80 = <<90-80=10>>10 more dollars
Since 50 cents is ½ dollar, then the number of bottles required to get 10 dollars is 10 / (1/2) = 10*2 = <<10/(1/2)=20>>20 bottles.
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