Question

A 450 gallon tank full of water is draining at a rate of 20 gallons per minute. We can represent the situation with the equation:

y
=
450
−
20
x
y
=
450
-
20
⁢
x

where x is the number of minutes that have passed by, and y is the amount of water in the tank. How long will it take for the tank to have 200 gallons?

A.
12.5 minutes

B.
32.5 minutes

C.
2.15 minutes

D.
20 minutes

Answer 1

Replace y with 200 ( amount of water in the tank) and solve for x:

200 = 450 -20x

Subtract 450 from both sides:

-250 = -20x

Divide both sides by-20:

X = 12.5

The answer is A. 12.5 minutes