Answer
$P_{1}=102.74kPa$
Work Step by Step
$P_{atm}=(758mm Hg)*(\frac{0.1333kPa}{1mm Hg})=101.04kPa$
Solving the manometer:
$P_{atm}+\gamma_{B}*h_{B}+\gamma_{A}*h_{A}=P_{1}$
$P_{1}=101.04kPa+8\frac{kN}{m^3}*0.15m+10\frac{kN}{m^3}*0.05m$
$P_{1}=102.74kPa$