Final answer:
The length of PQ cannot be determined based on the given information.
Step-by-step explanation:
In a rectangle, opposite sides are equal in length. Therefore, if SP = 4 and PR = 5, then we can conclude that SQ = 4 and QR = 5. In a rectangle, PQ and SR are also equal in length. So, PQ must be equal to SR and can be found by subtracting QR from SP: PQ = SP - QR = 4 - 5 = -1.
However, the length of a side cannot be negative. So, in this case, it is not possible to determine the length of PQ based on the given information.