Sam is currently 18 / 3 = <<18/3=6>>6 years old.
Sue is currently 6 / 2 = <<6/2=3>>3 years old.
In three years, Sue will be 3 + 3 = <<3+3=6>>6.
In three years, Same will be 6 + 3 = <<6+3=9>>9.
In three years, Kendra will be 18 + 3 = <<18+3=21>>21.
Their total age in three years is 6 + 9 + 21 = <<6+9+21=36>>36.
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