Answer:
I think the answer would be C, because
Explanation:
Example:
If in 6(x) years Robert is 16(k), how old was he 3(m) years ago?
First, you would have to find out how old Robert is now, 16-6=10
Then, you would take 10, his current age, and subtract 3(m) 10-3=7
I hope this helped, good luck!