A child is 17 years old. His father told him, "In 13 years, you will have one third of my age." What is the age of the father?

Let the current age of the child be C and the current age of the father be F.

According to the given information, in 13 years, the child will be C + 13 years old and the father will be F + 13 years old.

It is also given that in 13 years, the child will have one third of the father's age. So we can write the following equation:

C + 13 = (1/3)(F + 13)

Now, we know that the current age of the child is 17 years old. So we can substitute C = 17 into the equation:

17 + 13 = (1/3)(F + 13)

30 = (1/3)(F + 13)

Multiplying both sides by 3:

90 = F + 13

Subtracting 13 from both sides:

F = 77

Therefore, the current age of the father is 77 years old.

Let's represent the current age of the father as "x". According to the given statement, in 13 years, the child's age will be one-third of the father's age.

We can write an equation based on this information:

Child's age in 13 years = (1/3) - Father's age in 13 years

Since the child is currently 17 years old, his age in 13 years will be 17 + 13 = 30 years.

Substituting these values into the equation, we get:

30 = (1/3) - (x + 13)

Multiplying both sides by 3 to isolate x:

90 = x + 13

Subtracting 13 from both sides:

77 = x

Therefore, the current age of the father is 77 years old.