A mercury-filled manometer with two unequal-length arms of the same cross sectional area is sealed off with the same pressure p in the two arms, as in fig. 21-23. With the temperature constant, an additional 10.0 cm3 of mercury is admitted through the stopcock at the bottom. The level on the left increases 6.00 cm and that on the right increases 4.00 cm. Find the pressure p.