Answer:
When Marco is 24, Yohan will be 15.
Step-by-step explanation:
To find this, you can subtract Marco's current age, 18, from his future age, 24, to find the number of years that have passed. Then, add that number of years to Yohan's current age to find his future age. In this case, the number of years that will have passed is 24 - 18 = 6 years. When you add 6 years to Yohan's current age of 9, you get 9 + 6 = 15. Therefore, when Marco is 24, Yohan will be 15.