When writing a repeating decimal as a fraction, why does the fraction always have only 9s or 9s and 0s as digits in the denominator

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?

Find the value of x to the nearest tenth. a. 4.5 b. 5.4 c. 6.3 d. 7.2

Find the cocordinatse of the point on y axis which is nearest to the point (-2,5)