When it is not mentioned that the addressing of memory cells in byte addressable or word addressable manner , then the default assumption is to take byte addressable , meaning that the word size of a memory cell to be taken = 1 byte
We know in PC relative addressing mode , PC value is updated as :
PC (new value) = PC(current value) + Displacement(Given in address field of instruction)
So given current value of PC = 516 (As instruction is 4 bytes long and it is byte addressable)
And given , new value of PC = 885
Therefore , the displacement is found as :
516 + x = 885
==> x = 369