First term a = 1
Second term t1 = 2
Third term t3 = 3
Common difference d = t3 – t2 = 3 – 2 = 1
We need to find total number of trees when n = 25
Thus, by using sum of nth term of an A.P. we will find its sum
![Maharashtra Board Solutions for Class 10 Maths Part 1 Chapter3 Maharashtra Board Solutions for Class 10 Maths Part 1 Chapter 2 - Image 29](https://cdn1.byjus.com/wp-content/uploads/2020/04/maharashtra-board-solutions-for-class-10-maths-part-1-chapter-2-image-291.png)
Where, n = no. of terms
a = first term
d = common difference
Sn = sum of n terms
We need to find S25
Thus, on substituting the given value in formula we get,
![Maharashtra Board Solutions for Class 10 Maths Part 1 Chapter3 Maharashtra Board Solutions for Class 10 Maths Part 1 Chapter 2 - Image 30](https://cdn1.byjus.com/wp-content/uploads/2020/04/maharashtra-board-solutions-for-class-10-maths-part-1-chapter-2-image-301.png)