for the first drain the equation you need would be: 2n = 108
for drain B your equation would be: 5n = 108
these are your equations because a number times the amount of water the drain drains per minute will equal 108
to solve use inverse operations and divide 108 by the amount of water the drain drains in one minutes
Drain A- 108/2 = 54
it takes 54 minutes for drain a to empty a pool with 108 gallons of water
Drain B- 108/5 = 21.6
it takes 21.6 minutes for drain b to empty a pool with 108 gallons of water in it