Answer
(a) $\tau = 519~N~m$
(b) $Work = 3260~J$
Work Step by Step
(a) $P = \tau ~\omega$
$\tau = \frac{P}{\omega}$
$\tau = \frac{(175~hp)(746~W/hp)}{(2400~rev/min)(1~min/60~s)(2\pi~rad/rev)}$
$\tau = 519~N~m$
(b) $Work = \tau~\theta$
$Work = (519~N~m)(2\pi~rad)$
$Work = 3260~J$