Each side of the flag is 20 square feet because 5 x 4 = <<5*4=20>>20
Both side total to 40 square feet because 2 x 20 = <<2*20=40>>40
He will need 10 quarts because 40 / 4 = <<40/4=10>>10
This will cost $20 because 10 x 2 = <<10*2=20>>20
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