Answer: Susan is 16 years old.
Explanation:
Let x represent Susan's age.
Bob's age is 4 times greater than Suzan's age. This means that Bob's age is 4x.
Dakota is three years younger than Suzan. This means that Dakota's age is x - 3
The sum of Bob's, Suzan's, and Dakota's age is 93. This means that
4x + x - 3 + x = 93
4x + x + x = 93 + 3
6x = 96
x = 96/6 = 16
Bob's age = 4x = 4 × 16 = 64
Dakota's age = x - 3 = 16 - 3 = 13