Calculate the minimum pressure in order for a condenser, operated at $105\backslash$deg C$,$ to completely condense a vapor containing $70\%$ methanol $($A$)$ and $30\%$ ethanol $($B$).$ At $105\backslash$deg C: PA$-$sat $=1\mathrm{.}8$ bar, PB$-$sat $=1\mathrm{.}2$ bar.

B$.$ calculate the pressure at which a first droplet would start to condense out. Assume ideal solution behavior for the alcohol mixture.