Each year a tree grows 5 cm less than it did the preceding year. If it grew by 1 m in the last year, it eased growing. Find that, in which year does it stop its growing ?

Anyone please help me.............
Because its too urgent..........
Please check the sum properly. The sum may not be correct.
whatttt?????????? i did not completely understand the question.


The Brainliest Answer!
Hey its part of an Arithmetic progression
an Arithmetic progression(AP) is a sequence of numbers in which each differs from the preceding one by a constant quantity
in which
a(first term)  = 100 cm
d(common difference) = - 5cm
An(nth term) = 0cm
n = ?
An = a + (n-1)d
0 = 100 - 5n + 5
-105 = - 5n
21 = n 
hence in the 21 st year the tree will stop growing
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2 5 2