1. Find Shawn's current age:
* Shawn is 16 years younger than Tanya, so he is 18 - 16 = 2 years old.
2. Set up an equation:
* Let 'x' be the number of years it takes for Tanya to be three times Shawn's age.
* In 'x' years, Tanya will be 18 + x years old.
* In 'x' years, Shawn will be 2 + x years old.
* We want Tanya's age to be three times Shawn's age, so: 18 + x = 3(2 + x)
3. Solve the equation:
* 18 + x = 6 + 3x
* 12 = 2x
* x = 6
4. Find their ages when Tanya is three times Shawn's age:
* Tanya will be 18 + 6 = 24 years old.
* Shawn will be 2 + 6 = 8 years old.
Answer: Tanya will be 24 years old when she is three times Shawn's age (who will be 8 years old).