Total vapor pressure can be calculated using partial vapor pressures and mole fraction as follows:

Here,
is mole fraction of A,
is mole fraction of B,
is partial pressure of A and
is partial pressure of B.
The mole fraction of A and B are related to each other as follows:

In this problem, A is hexane and B is octane, mole fraction of hexane is given 0.580 thus, mole fraction of octane can be calculated as follows:

Partial pressure of hexane and octane is given 183 mmHg and 59.2 mmHg respectively.
Now, vapor pressure can be calculated as follows:

Putting the values,

Therefore, total vapor pressure over the solution of hexane and octane is 131 mmHg.
Answer:
S + 02= S0 - 4 e- → SIV (oxidation); 2 O0 + 4 e- → 2 O-II (reduction)
C + 02= C
Cu0 + H2SO4= CuO + H2SO4 → CuSO4 + H2O