EXAMPLE $1$: Humidity from Vapor$-$Pressure Data

The air in a room is at $26\mathrm{.}7C$ and a pressure of $101\mathrm{.}325$kPa and contains water vapor with a partial pressure $p_A=2\mathrm{.}76$kPa. Calculate the following:

$($a$)$ Humidity, $H.($b$)$ Saturation humidity, $H_s$ and percentage humidity, $H_p.($c$)$ Percentage relative humidity, $H_R$