Question

• Water tank A has 220 gallons of water and is being drained at a constant rate of 5 gallons per minute.

• Water tank B has 180 gallons of water and is being drained at a constant rate of 3 gallons per minute.
Part
How much time, in minutes, do water tank A and water tank B have to be drained in order for them to have the same amount of water?

Answer 1

Answer: In 20 minutes, tanks A and B will each have 120 gallons remaining in them.

Explanation:

The equation, the amount at which they will be equal, represents the given starting amounts minus the gal/min times the unknown time in minutes, m.

220 - 5m = 180 - 3m Subtract 180 from both sides; add 5m to both sides.

220-180 -5m +5m = 180-180 +5m - 3m Combine like terms

40 = 2m Divide both sides by 2

20 = m

Check: Substitute 20 for m in the equation

220 - 5(20) = 180 - 3(20)

220 - 100 = 180 -60

120 = 120 True!