The total pressure of a mixture of co2 and o2 is 780 mmhg. if the pressure of the co2 is 560. torr, what is the pressure of o2?

When the total pressure equal sum of all the partial pressure with the same units.

and when we have total pressure = 780 mmHg = 780 torr

So total pressure = P(CO2) + P(O2)

by substitution:

780 torr = 560 torr + P(O2)
∴P(O2) = 780 torr - 560 torr
             = 220 torr