# total area problem

#### postmaster

##### New member
Find the total area of the walls of a rectangular room that has 10-foot ceilings and
is 15 feet by 12 feet. There is a door that is 7 feet high by 3 feet wide, and two
windows that are each 4 feet high by 2 feet wide. (Subtract the area of the door
and windows from the total area.)

* I know this is really basic, but I couldn't come at the correct answer which is 503 sq ft. will be grateful if someone could explain the math to me. thanks!

#### Subhotosh Khan

##### Super Moderator
Staff member
Find the total area of the walls of a rectangular room that has 10-foot ceilings and
is 15 feet by 12 feet. There is a door that is 7 feet high by 3 feet wide, and two
windows that are each 4 feet high by 2 feet wide. (Subtract the area of the door
and windows from the total area.)

* I know this is really basic, but I couldn't come at the correct answer which is 503 sq ft. will be grateful if someone could explain the math to me. thanks!
Quick mental math gives me the "reported" answer.

Please show us what you have tried (in detail) and exactly where you are stuck.

Please follow the rules of posting in this forum, as enunciated at:

#### postmaster

##### New member

the total area of the two side walls = (15*12)+ (15*12)= 360
total area of the two walls with the windows and door = (10*15)+(10*15)=300
after subtracting the areas of windows and the door = 300- (7*3)-2*(4*2)=263
total area of the room = (360+263)= 623
* I am sensing there's a very stupid mistake involved. would appreciate if you could kindly explain the correct math!

#### HallsofIvy

##### Elite Member
Find the total area of the walls of a rectangular room that has 10-foot ceilings and
is 15 feet by 12 feet. There is a door that is 7 feet high by 3 feet wide, and two
windows that are each 4 feet high by 2 feet wide. (Subtract the area of the door
and windows from the total area.)

* I know this is really basic, but I couldn't come at the correct answer which is 503 sq ft. will be grateful if someone could explain the math to me. thanks!
There are two walls that are 15 by 10 feet and two walls that are 12 by 10 feet. Calculate the total area of those four walls then subtract the total area of the 7 by 3 feet door and the two 4 by 2 feet windows. When I do that I get 503 square feet. Please show what you did and what answer you got!

#### Dr.Peterson

##### Elite Member
Find the total area of the walls of a rectangular room that has 10-foot ceilings and
is 15 feet by 12 feet. There is a door that is 7 feet high by 3 feet wide, and two
windows that are each 4 feet high by 2 feet wide. (Subtract the area of the door
and windows from the total area.)

* I know this is really basic, but I couldn't come at the correct answer which is 503 sq ft. will be grateful if someone could explain the math to me. thanks!
First ignore the door and windows, and find the areas of the rectangular walls. Then find the area of each door and window, and subtract them from the total.

When you show your work, we can tell where you are making an error. Possibly, for example, you counted only two walls rather than four; or maybe you found the area of the ceiling.

#### Subhotosh Khan

##### Super Moderator
Staff member

the total area of the two side walls = (15*12)+ (15*12)= 360
total area of the two walls with the windows and door = (10*15)+(10*15)=300
after subtracting the areas of windows and the door = 300- (7*3)-2*(4*2)=263
total area of the room = (360+263)= 623
* I am sensing there's a very stupid mistake involved. would appreciate if you could kindly explain the correct math!
One side of every wall is 10' (tall - the height of the roof). So

Total the area of the walls = 15*10 + 12*10 + 15*10 + 12*10 = 540 sq.ft.

Area of door = 7*3 = 21 sq.ft.

Area of 2 windows = 2 * 4*2 = 16 sq.ft.

Total paintable surface = 540 - 21 - 16 = 503 sq.ft.

#### Jomo

##### Elite Member
One side of every wall is 10' (tall - the height of the roof). So

Total the area of the walls = 15*10 + 12*10 + 15*10 + 12*10 = 540 sq.ft.

Area of door = 7*3 = 21 sq.ft.

Area of 2 windows = 2 * 4*2 = 16 sq.ft.

Total paintable surface = 540 - 21 - 16 = 503 sq.ft.
You don't paint the ceiling? Why not? BTW, I do know that the ceiling is not a wall.