Explanation:
Well seeing as each year the amount of Trees Doubled (7+7=14 and 14+14=28)
We can Infer that each year afterwards it will do so.
So 1 year from now 28+28 = 56
2 years from now 56 + 56 = 112
And finally at 3 years 112+112 we arrive at our answer 224
Answer: So it would take 3 years to get to get to 224