Question

A water tank holds 486 gallons but leaking at a rate 4 gallons per week. A second water tank holds 648 gallons but is leaking at a rate of 7 gallons per week. After how many weeks will the amount of water in the 2 tanks? The amount of water that holds the two tanks will be the same in _ weeks.

Answer 1

The first tank contains

486 gal - (4 gal/week) t

gal of water after t weeks.

Similarly, the second tank contains

648 gal - (7 gal/week) t

gal of water.

The tanks hold the same amount of water when these two amounts are equal:

486 gal - (4 gal/week) t = 648 gal - (7 gal/week) t

(7 gal/week) t - (4 gal/week) t = 648 gal - 486 gal

(3 gal/week) t = 162 gal

t = (162 gal) / (3 gal/week)

t = 54 weeks