Answer: Check the explanation for the solution.
Step-by-step explanation:
Given that the garden is a right triangle with base 25m start and height 30 m
The length of the hypothenus can be achieved by using pythagorean theorem.
Please find the attached file for the diagram.
I made a large unit for the sake of clarity.
The Given Sequence is an Arithmetic Sequence with First term = -19
⇒ a = -19
Second term is -13
We know that Common difference is Difference of second term and first term.
⇒ Common Difference (d) = -13 + 19 = 6
We know that Sum of n terms is given by : 
Given n = 63 and we found a = -19 and d = 6






The Sum of First 63 terms is 10521