partial pressure is the pressure that is exerted by individual gases.
Partial pressure is calculated as the product of total pressure by the mole fraction of the corresponding gas.
pressures exerted by gases are in three different units, therefore we can convert them all into a common unit - torr
1 - 0.845 atm - 0.854 atm x 760 Torr/atm = 642 torr
2 - 120 torr
3 - 210 mmHg - 1 mmhg is almost equivalent to 1 torr - therefore its 210 torr
total pressure - 642 + 120 + 210 = 972 torr
answer is 972 torr
