120 gallons in 4 days.....120/4 = 30 gallons per day
for 28 days...
30 * 28 = 840 gallons <==
Now go to school...lol
Answer:
or 
Step-by-step explanation:
we know that
The surface area of a cube is equal to

where
x is the length side of a cube
In this problem we have

substitute in the formula and solve for x


square root both sides

The letter "x" is often used in algebra to mean a value that is not yet known. It is called a "variable" or sometimes an "unknown". In x + 2 = 7, x is a variable