Question

Marco is draining his two aquariums. The tanks are the same size. One tank has 7 in. of water in it and is being drained at a rate of 1 in./min. The other tank has 5 in. of water in it and is being drained at a rate of 0.5 in./min. After how many minutes will the tanks contain the same amount of water?

Remember to enter a numerical answer.

Answer 1

Let x be the number of minutes it takes for the two tanks to contain the same amount of water, then
7 - x = 5 - 0.5x
-0.5x + x = 7 - 5
0.5x = 2
x = 2/0.5
x = 4 mins

Therefore, the tanks will contain the same amount of water after 4 mins.