A gasoline line is connected to the atmosphere through a double$-$U manometer, as shown below.

$h1=39\mathrm{.}0cm,h3=13\mathrm{.}1cm$ and $h4=20\mathrm{.}0cm.$ The densities of water, oil, mercury and gasoline are

$1000,780,13500$ and $720k\frac{g}{m^3},$ respectively. The absolute pressure of the gasoline is $70\mathrm{.}0$kPa

and the atmosphere pressure is $100$kPa.

a$)$ Determine h$2.$

$(8$ marks$)$

b$)$ The pressure of the gasoline in the pipe decreases by $3\mathrm{.}50$kPa. Determine the new h$1,$ h$2,$ h$3$

and h$4.($Hint: you should expect that the liquid columns shift to one side due to the pressure

change. You can calculate the shift $(h)$ first.$).$