Answer:
264/70, or 3.77142857.
Explanation:
You can first calculate how much paint is needed for the bottom part.
Do 18*12 to do this, and you'll find that 216 sq ft is needed for that.
You can then calculate the top, or the triangle part.
The formula for area of a triangle is .5b*h.
The base is 12 feet, and the height is 10 feet, as you can find this by doing 28-18.
Putting this in the formula, you'll find that the entire triangle is .5*12*10 = 60.
However, you have to get rid of the window at the top, so do 4*3 (dimensions of the window), and subtract that from 60, which = 48.
Now, with values from the bottom part and the top part, you can add them together to get how much sq ft it is. 216+48= 264.
Now, you will do 264/70 to find how many gallons you need. This = around 3.77.