Answer
$P_{w}-P_{sw}=8.34kPa$
Work Step by Step
Solving the manometer:
$P_{w}+\rho_{w}*g*h_{w}-\rho_{Hg}*g*h_{Hg}-\rho_{oil}*g*h_{oil}+\rho_{sw}*g*h_{sw}=P_{sw}$
$P_{w}-P_{sw}=g*(-\rho_{w}*h_{w}+\rho_{Hg}*h_{Hg}+\rho_{oil}*h_{oil}-\rho_{sw}*h_{sw})$
Substituting:
$P_{w}-P_{sw}=(9.81\frac{m}{s^2})*(-1000\frac{kg}{m^3}*0.6m+13600\frac{kg}{m^3}*0.1m+(0.72*1000\frac{kg}{m^3})*0.7-1035\frac{kg}{m^3}*0.4)$
$P_{w}-P_{sw}=8.34kPa$
