Question 338562
Find the total area to cover the ceiling.
The ceiling is in the shape of a rectangle.
The area of a rectangle is length times width.
{{{A=L*W=21*18}}}sq.ft.
Each tile is a 1'x1' square and has an area of 1 sq. ft.
Divide the total area by the area of one tile to find out how many tiles you need.
{{{N=A/1}}}
The total cost is $3 times the number of tiles.
{{{C=3N=(3A)/1=(3*21*18)/1}}} in dollars.