[Timothy]

How do I calculate the residual pressure in the isoteniscope from the following data using this equation P = P[atm]-dg(hi-hE) where hi is internal reading and hE is external reading of mercury. The values are d for mercury 13550 kg.m^-3, g = 9.807 m.s^-2, hi = 79.20mmHg, hE = 26.10mm Hg. Barometric pressure of the day was 707.30mmHg.

This was what I tried;

P = 94333.575 - (13550)(9.807)(7079.42), note 79.20-26.10 = 53.10 mmHg = 7079.42Pa and 707. 30 mmHg =     
94333.575 Pa
  = -940653366 Pa

How do I get the correct answer. Any help would be greatly appreciated.

Thanks