In parallelogram OPMN , diagonal PN divides it into two congruence triangle OPN and NMP.
area of triangle (OPN) = area of triangle (PMN)
Area of Triangle (PMN)=(1/2) area of parallelogram OPMN
=(1/2) . 48
area of traingle (PMN)= (1/2) x 3 x PN
24 = (1/2) x 3 x PN
PN = 16 unit