How many gallons of paint are necessary to paint the walls of a 15' by 12' room room with an 8' ceiling if one gallon of paint covers 80 square feet?

gallons=1gallon/80ft^2 * 15x12

To calculate the number of gallons of paint necessary to paint the walls of a room, we need to determine the total surface area of the walls and divide it by the coverage provided by one gallon of paint.

First, let's calculate the total area of the walls. Since the room has four walls, we need to find the sum of the areas of each wall.

The walls with dimensions 15' by 8' and 15' by 8' are adjacent to each other and have the same height, so we can calculate their combined area.

Area of first set of adjacent walls = 2 * length * height
= 2 * 15' * 8'

The walls with dimensions 12' by 8' and 12' by 8' are opposite each other and have the same height, so we can calculate their combined area as well.

Area of second set of adjacent walls = 2 * width * height
= 2 * 12' * 8'

Now, we can calculate the total area of all the walls.

Total wall area = Area of first set of adjacent walls + Area of second set of adjacent walls
= 2 * 15' * 8' + 2 * 12' * 8'

To find the answer in gallons, we need to know the coverage provided by one gallon of paint, which is stated as 80 square feet.

Number of gallons of paint necessary = Total wall area / Coverage per gallon
= (2 * 15' * 8' + 2 * 12' * 8') / 80 square feet

Now, let's calculate the number of gallons of paint required.

Total wall area = (2 * 15' * 8' + 2 * 12' * 8') = 256 square feet
Coverage per gallon = 80 square feet

Number of gallons of paint necessary = Total wall area / Coverage per gallon
= 256 square feet / 80 square feet
= 3.2 gallons

Therefore, you would need approximately 3.2 gallons of paint to cover the walls of the given room.