Solution:
1. Determine how many years have passed since the time when Marko was 12.
- Current year: 2025
- Three years ago: 2025 - 3 = 2022
2. Use the information that Marko was 12 years old in 2022 to find his age in 2025.
- Marko was 12 years old in 2022.
- Number of years from 2022 to 2025: 2025 - 2022 = 3
3. Calculate Marko's age in 2025:
- Marko's age in 2025: 12 + 3 = 15