Phase of this AC circuit
Convert the resistors to one value using Thevenin's Theorem. In simple terms this is the parallel combination of R1 and R2 = 3.0769 ohms. The reactance is simply 9 ohms at 50 Hz and is in-series with the new value of resistor.

The combined impedance is 3.0769 + j9 or \$9.511\space \Omega \space \angle{71.125}\$

This means the current lags the input voltage by 71.125 degrees.