question: Vincent can buy flowers in packages of 3 for $2.50 or in packages of 2 for $1. How much money does he save by buying 18 flowers at the better price?
answer: Find how many packages of 3 would be needed which is 18 ÷ 3 = <<18/3=6>>6.
  The cost of using packages of 3 is 6 × $2.50 = $<<6*2.5=15>>15.
  Find how many packages of 2 would be needed which is 18 ÷ 2 = <<18/2=9>>9.
  The cost of using packages of 2 is 9 × $1 = $<<9*1=9>>9.
  Vincent would save $15 - $9 = $<<15-9=6>>6.
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