Answer:
376 square centimeters
Step-by-step explanation:
When doubled, the new length is 5*2=10 cm, new width is 4*2=8 cm, and new height is 3*2=6 cm.
The surface area of a rectangular prism is given by : 
Where l is length, w is width, and h is height
Plugging in the new values we get:
The surface area of the enlarged prism = 376 cm^2
1/the rate of leakage per hour
This will give you the time it takes for 1 gallon to leak out in hours.
For example, if something is leaking at the rate of 12 gallons per hour, it will take 1/12 of an hour for 1 gallon to leak out. ( or 5 min)
To find A' they used the rule of multiplication, which is:
the derivative of a product of two terms is the first term times the derivative of the second term plus the second term times the derivative of the first.
To find b' they just isolated b'
