Question

in a family the average age of a father and mother is 35 years old .The average age of the mother father and their son in 27 years old. what is the average age

Answer 1

Avg of father and mother
F+M/2=35
F+M=70
avg of father mother and son
F+M+S/3=27
F+M+S=81
S=81-70=11