Okay, so I've attached a bad drawing of what I think the problem is describing. The basic figure is a rectangular prism topped by a rectangular pyramid.

For partB, you want to determine the area of the floor and outside walls. There is one 9x7 floor, two 6x7 walls, and two 9x6 walls. So

Area

However, you have to remember to subtract the area of the door and windows, since they won't be painted. First we calculate the total area of the door and windows - there are four 2x2 windows and one 5x2 door. So

Area

Subtracting this area from the total, we get

Area

which is the area to be painted. To calculate the cost, we first need to find how much paint will be required. We know one can of paint will cover 125 ft, and we need to cover 229 feet. So clearly we will need two cans of paint. Then we add the cost of the paint and brushes: we need 2 cans of paint (24.99 each), a brush (6.99), and a roller brush (10.95). So

Cost

So for partB, you get an area of 229 square feet and a cost of $67.92. Can you go from there?