Answer
$\phi = -41.5^{\circ}$
Work Step by Step
We can find $\phi$:
$tan~\phi = \frac{-X_C}{R}$
$tan~\phi = \frac{-\frac{1}{\omega_d ~C}}{R}$
$tan~\phi = -\frac{1}{\omega_d ~C~R}$
$tan~\phi = -\frac{1}{2\pi~f_d ~C~R}$
$tan~\phi = -\frac{1}{(2\pi)~(60.0~Hz)~(15.0\times 10^{-6}~F)~(200~\Omega)}$
$tan~\phi = -0.8842$
$\phi = tan^{-1}~(-0.8842)$
$\phi = -41.5^{\circ}$
