Acc to qn
AP:4,1+4,1+1+4,and so on
i.e,4,5,6,7,8 and so on
22nd year ,he planted 4: 23rd , he planted 5 and so on
So we should find how many trees were planted on the 40th year.
So (40-22)+1 will give the total number of years.
So we should find a19 because 40-22 +1 =19
an=a+(n-1)d
a=4
n=19
d=1(5-4)
Substituting the values
a19=4+(19-1)1
a19=4+ 18 =>22
therefore,22 trees will be planted on the 40th year.
VERIFICATION
4 trees=22nd year, 5 trees=23rd year and when u do it in the same manner u will get 22 trees=40th year
Hope u find it helpful
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