Let x be the original width of the square dance floor.
In the rectangle:
Length = x + 15
Width = x - 10
Therefore, the difference between length and width = 25.
Perimeter = 2length + 2width
130=2(x + 15) + 2(x - 10)
130=2x + 30 + 2x -20
130 = 4x + 10
130 - 10 = 4x
x = 120/4
x = 30
Length = x + 15 = 30 + 15 = 45
Width = x - 10 = 30 - 10 = 20
Therefore, the length of the dance floor is 45 feet and the width is 20 feet
The number of tiles is the area of the dance floor because each tile is 1 foot by 1 foot.
Area = length * width
Area = 45 * 20
Area = 900 feet²
Thus, she needs 900 tiles. Each tiles costs $0.50 so,
Total cost = 900 tiles * $ 0.50 = $450.00