A furniture manufacturer has two machines, but only one can be used at a time.

A furniture manufacturer has two machines, but only one can be used at a time. Machine A is utilized during the first shift and Machine B during the second shift, while both works half of the third shift. If Machine A can do the job in 12 days working two shifts and Machine B can do the job in 15 days working two shifts, how many days will it take to do the job with the current work schedule?

9. Two cities A and B are 30 km apart. From both of these cities, simultaneously, two hikers start their journeys towards each other.

Two cities A and B are 30 km apart. From both of these cities, simultaneously, two hikers start their journeys towards each other. They are walking at a constant speed of 5 km/hour each. Simultaneously, a fly leaves the city A. It flies at the speed of 10 km/hour and passes the hiker from its city. When it reaches the B hiker, it turns around and flies back to A hiker. It keeps doing so until the hikers meet.