(1) It takes x hours to set up two factories, A and B, to process at the same time.

De: (55+45)x=700

Solution: x=7

A: It takes seven hours a day for two factories to process at the same time.

(2) It takes y hours to build a factory.

From the title, it can be known that the cost per ton of garbage is 550/55= 10 yuan.

The cost of garbage disposal per ton in Plant B is 495/45= 1 1 yuan).

Then there is 550 y+11(700-55y) ≤ 7370.

Solution: y≥6

A: Factory A needs at least 6 hours to dispose of garbage every day.