Final answer:
To solve this problem, we can find the current ages of Natalie and Chris using a simple equation. Then, we can calculate their ages 18 years from now to find the ratio. The ratio of Chris to Natalie's age 18 years from now is 85:136.
Step-by-step explanation:
To solve this problem, let's first find the current ages of Natalie and Chris. Let's say Natalie's current age is x. Since Chris is 5/8 of Natalie's age, his current age is (5/8)x.
In 12 years' time, Natalie's age will be x + 12, and Chris's age will be (5/8)x + 12. We know that their total age will be 50, so we can write the equation: (x + 12) + ((5/8)x + 12) = 50.
Simplifying this equation, we get (13/8)x + 24 = 50. Subtracting 24 from both sides gives us (13/8)x = 26. Multiplying both sides by 8/13, we find x = 16.
Now, we need to find the ratio of Chris to Natalie's age 18 years from now. In 18 years, Natalie's age will be 16 + 18 = 34, and Chris's age will be (5/8) * 34 = 21.25. Therefore, the ratio of Chris to Natalie's age 18 years from now is 21.25:34, which simplifies to 85:136.