Question

Salt water is poured into a U tube until it stands 0.250 m high in each arm. Oil is then added slowly to one arm until the salt water in the other arm stands 0.300 m high. The free surface of the oil then stands at 0.321 m high. (the weight density of the salt water is 10,100N/m^3)
What is the absolute pressure at the bottom of the u tube?
What is the mass density of the oil?

So for the salt water, the mass density i got was 1030kg/m^3. The height of left arm with only salt water increased 0.05m after oil was added. and i know P = phg, the arm with salt water has bigger pressure than the oil arm.
But i am lost for the rest. plz help