All we can determine from the information that you have given us is that
yz should be proportionally related to bc, because their triangles are similar.
X2 - 2x + 9x - 18
X2 + 7x - 18
12^2+x^2=15^2
144+x^2=225
- 144 -144
=81= 9
X=9
The probability that both specific qualified applicants will be among the eight selected is given by:

The probability that the two will get apartments on the North side is given by:

The probability that the two will get apartments on the South side is given by:

The events '2 apartments on North side' and '2 apartments on South side' are mutually exclusive. Therefore the probability the two specific qualified applicants will be on the same side of town is 0.107 + 0.357 = 0.464.
Finally, the probability that two specific qualified applicants will be selected for apartments on the same side of town is found from: