Ineed with: 100 textbooks increased by 99%. is it 199? ?

When solving this problem: 3025/5.5 = a/90.75 you get 49912.5 which would be the length of one of the sides of a square when the area is only 90.75 inches. is that answer correct, why, and how is it possible?

If t17 = 3 (t5) in an arithmetic progression, find t1 in terms of d.

Ineed the solution to this problem and the steps.