please help me understand the answer and what table to use. thank you

3. Find the value of X2 values that separate the middle 80 % from the rest of the distribution for 9 degrees of freedom. In this case, we have 1-.80=.20 outside of the middle or .20/2 = .1 in each of the tails. Notice that the area to the right of the first X2 is .80'+ .10 = .90. So we use this value and a DOF of 9 to get X2 = 4.168. The area to the right of the second X2 is .10. So we use this value and a DOF of 9 to get X2 = 14.684