Answer:
It doesn't say what to do with that 0.1 of a gallon. I would buy another gallon or dilute what I had so it came to exactly 9.1 gallons. In math, I suppose the answer is 9.
In reality it would be 10.
You have to choose. What has been done with other questions like this.
Explanation:
1 can covers 55 square feet.
h = 10
w1 = 10 feet
w2 = 10 feet
w3 = 15 feet
w4 = 15 feet
Total area = Area of wall 1 + wall 2 + wall 3 + wall 4
Total area = 10*10 + 10*10 + 10*15 + 10* 15
Total area = 100 + 100 + 150 + 150
Total area = 500 feet^2
1 gallon / 55 ft^2 = x / 500 ft^2 Cross multiply
55 * x = 500 Divide by 55
x = 500/55
x = 9.1 gallons.
In real life you would buy another gallon.