Answer
The mass of this quasar is being reduced at a rate of $~~17.5~smu/year$
Work Step by Step
We can find the amount of mass that is converted into energy each year:
$mc^2 = (10^{41}~W)(365*24*3600~s)$
$m = \frac{(10^{41}~W)(365*24*3600~s)}{c^2}$
$m = \frac{(10^{41}~W)(365*24*3600~s)}{(3.0\times 10^8~m/s)^2}$
$m = 3.504\times 10^{31}~kg$
$m = \frac{3.504\times 10^{31}~kg}{2.0\times 10^{30}~kg/smu}$
$m = 17.5~smu$
The mass of this quasar is being reduced at a rate of $~~17.5~smu/year$
