Answer:
75%
Explanation:
Since the production center is available for 8 hours per day in a factory, and the worker operating it is required to lubricate these rotary parts once each day.
If it takes 2 hours to remove these parts from the equipment, lubricate them, and re-assemble them and the production center is not available for production during these times;
Then the availability of the production center is 75% which is derived by : [8 hours total - 2 hours downtime / 8 hours total availability] x 100 = 75%