Answer:
0 = 208 - 12x
Explanation:
Since after 5 days the tree only had 208 leaves remaining, assuming that the rate of decay is constant, we can use the following equation to calculate the total number of days (starting at the 5-day mark as 0) until the tree loses all of its leaves. In this equation, the total number of days is represented by the variable x.
0 = 208 - 12x
Now that we have the equation we can solve it...
0 = 208 - 12x ... subtract 208 on both sides
-208 = -12x ... divide both sides by -12
17.33 = x
Finally, we can see that after 18 days (not 17.33 because we are counting full days) the tree will have lost all of its leaves.