Q21.Pressure of water = pgh = 1000*9.81*(2000-X)
Pressure of oil = pgh = 830*9.81*X
Total Pressure = 17.5*10^6 Pa(From Mega *one million)
17.5*10^6 = (19620000 - 9810X) + 8142.3X
(17.5*10^6) - (1.962*10^7) = -9810X + 8142.3X
-2.12*10^6 = -1667.7X
X = -2.12*10^6
------------ = 1270 to 3 sf
-1667.7
Hope it helped