Susanne is 16 years old.
b = Bob's age
s = Susanne's age
d = Dakota's age
Bob's age is 4 times greater than Susanne's age:
b = 4s
Dakota is three years younger than Susanne:
d = s - 3
The sum of Bob's, Susanne's, and Dakota's ages is 93:
b + s + d = 93
solve these equations:
b = 4s
d = s - 3
b + s + d = 93
and get:
b = 64 years
s = 16 years
(remember that s = Susanne)
d = 13 years
