Question 1006967
Imagine machine A working from 8 am until 1 pm.
In those five hours, it produces 5(1500) = 7500 paper clips.
That means there are 23,500 - 7,500 = 16,000 paper clips to go.
When both machines run, they produce 1500+2500 = 4,000 paper clips an hour.
Since they have to make 16,000 more paper clips, they work together for 16,000/4,000 = 4 more hours.
They will be done at 5 pm.