If Kaydence's father is 60 years old, her mother is 60-2 = <<60-2=58>>58 years old.
The total age of the mother and father is 60+58 = <<60+58=118>>118 years
Kaydence's brother is half the father's age, which is 1/2*60 =<<1/2*60=30>>30 years.
The total age of Kaydence's father, mother, and brother is 30+118= <<30+118=148>>148 years.
If you add Kaydence's sister's age to the total age of the father, mother, and brother, you get 148+40 = <<148+40=188>>188 years.
If everyone's age in the family is 200, then Kaydence's age is 200-188 = <<200-188=12>>12 years old.
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