Ann had 3 dozen oatmeal cookies - 2 dozen = <<3-2=1>>1 dozen oatmeal cookies left.
Ann had 2 dozen sugar cookies - 1.5 dozen = <<2-1.5=.5>>.5 dozen sugar cookies left.
Ann had 4 dozen chocolate chip cookies - 2.5 dozen = 1.5 dozen chocolate chip cookies left.
Ann has a total of 1 + .5 + 1.5 dozen cookies = <<1+.5+1.5=3>>3 dozen cookies.
3 dozen cookies is 3 *12 cookies = <<3*12=36>>36 cookies remaining.
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