To solve the problem, let's define the variables and set up the equations based on the information given:

1. Let the present age of Jean be \(x\) years.
2. According to the problem, John is twice as old as Jean. Therefore, John's present age is \(2x\) years.
3. It is given that after 3 years, the sum of their ages will be 66 years. In 3 years, Jean's age will be \((x + 3)\) and John's age will be \((2x + 3)\).
4. Set up the equation for the sum of their ages after 3 years: \((x + 3) + (2x + 3) = 66\)
5. Simplify the equation:
   • \(x + 3 + 2x + 3 = 66\)
   • \(3x + 6 = 66\)
   • Subtract 6 from both sides: \(3x = 60\)
   • Divide by 3: \(x = 20\)
6. So, Jean's present age is \(20\) years and John's present age is \(2 \times 20 = 40\) years.

Therefore, the present ages of Jean and John are 20 years and 40 years, respectively.

The correct answer is 20 and 40 years.

Let's verify this solution:

1. Jean's age after 3 years: \(20 + 3 = 23\) years.
2. John's age after 3 years: \(40 + 3 = 43\) years.
3. Sum of their ages after 3 years: \(23 + 43 = 66\) years, which matches the given condition.

This confirms that our solution is correct. The answer is validated.