chemistry... another manometer problem... production or consumption?

Question

i had the following problem in my chemistry book. the answer that i got was not the same as the answer from the book. perhaps somebody could explain it? the answer that i got was that it was a consumption and that the final pressure was 754.50 torr. apparently the answer was that it was a production and the final pressure was 826 torr.

here's the problem:

A student carried out a reaction using a bulb connected to an open-end mercury manometer on a day when the pressure was
746 torr. Before the reaction, the level of the mercury in both arms was at a height of 12.50 cm, measured by a meter stick placed
between the two arms of the U-shaped tube. After the reaction, the level in the arm connected to the bulb was at 8.50 cm. Did the
reaction produce or consume gases? What was the final pressure in the bulb (in torr)?

Answer 1

Since the reaction drove the mercury level down on the side connected to the bulb, the reaction must have resulted in production. The mercury levels were equal before the experiment, so a 4 cm drop on the bulb side caused a 4 cm rise on the open side, resulting in a ∆h of 8 cm or 80 mm. This corresponds to a pressure differential of 80 Torr. 746 + 80 = 826 Torr.