<5 is a supplement of <6, and m<5 = 78. Find m<6.

M<6=

We are given with a tank filling rate of the pipe of 8000 liter per hour. If the other pipe empties the tank in 3 hours, then the tanks has a volume of 8000l/hr * (3hr) equal to 24,000 liters. The answer is just the product of the rate and the time of emptying