350x8=2800, that's how much paint there is. In order to find the surface area of the fence, you just have to find the perimeter of the fence. so you do 45+60+45+60=220. and you have to multiply that by 6 because that is the height of the fence, which is 1320. Then you have to multiply that by 2 because you want to paint both sides of it right? so that's 2640. 2640<2880. So you can paint it with 8 gallons of pain. sorry it took me so long to understand.
Hope this helps you