power loss in AC circuit = (Vrms )2 R / ( √2 ) Z2
now we need to find Z ( impedance ),
Z = √( Xc - XL )2 + R2
now we need to find Xc and XL ,
Xc = 1 / ω C
XL = ω L
from the question, L = 20 mH
= 20 * 10-3 H
C = 100 µF
= 100 * 10-6 F
R = 50 Ω
VRMS = 10
ω = 314
after substituting Xc = 31.84
XL = 6.28
now put these values in Z
we'll get Z = 56.1 or 56
Z2 = 3136
now we can put the value of Z2 in power formula
P = (10)2 (50) / (√2) ( 3136)
= 0.79