If you use a laptop: 9.25; a desktop with a CRT monitor: 55.51; a desktop with an LCD monitor: 46.26.
A laptop that is plugged up and turned off uses 0.001kw/hr of energy. Each kwh of energy produces, on average, 1.39 lbs of CO2. There are 24*7=168 hours in the week; subtract the 40 hour work week from this and we have 128 hours a week for 52 weeks a year: 0.001*128*52=6.656*1.39=9.25.
A desktop that is plugged up and turned off uses 0.004kw/hr of energy. A CRT monitor uses 0.002 kw/hr when turned off. This means we have: (0.004*128*52*1.39)+(0.002*128*52*1.39)=55.51.
For a desktop and an LCD monitor, which uses 0.001 kw/hr of energy, we have: (0.004*128*52*139)+(0.001*128*52*1.39)=46.26.
70dB is represented by 100cars in 60sec. Therefore if the number of cats is reduced by 3/4 in the same amount of time(60s), then the decibel level will reduce by 3/4 also. So 70dB * .25= 17.5dB