Phosphorous trichloride (PCl3) is produced

Question

from the reaction of white phosphorous (P4)
and chlorine:
P4(s) + 6Cl2(g) ! 4 PCl3(g) .
A sample of PCl3 ofmass 280.7 g was collected
from the reaction of 70.86 g of P4 with excess
chlorine. What is the percentage yield of the
reaction?
Answer in units of %.