I found a similar problem with the same wording so that I can help you answer this question. To find the pressure, we use the formula for gauge pressure. Also, the conversion factor is: 1 atm = 760 mmHg,
Pabs = Patm - Pg = 0.995 atm - (520 mmHg)(1 atm/760 mmHg) = 0.31 atm
