Answer:
It will cost John $14 to paint his room.
Step-by-step explanation:
We have to calculate the whole area (in square feet) that John would have to paint. This area would include the area covered by the ceiling and walls, and exclude the area covered by the door and two windows:
1. Area covered by the ceiling = 14 × 8 = 112 square feet
2. Area covered by walls = perimeter of ceiling × height of wall = 2 × (14 + 8) × 7 = 308 square feet
3. Area covered by the door and two windows = (6 × 3) + (3 × 2.5 × 2) = 33 square feet
(Note: width of window = 30 inches = 2.5 feet)
Therefore, the area that would need to be painted = 112 + 308 — 33 = 387 square feet.
If John can use one quart to paint 100 square feet at $3.50, then he would need 3.87 quarts to paint 387 square feet; however, since he has to buy whole quarts, he would need 4 quarts instead of 3.87, and this would cost = 4 × 3.50 = $14