write an expression for the area of sidewalk using subtraction, overall area is 10 ft by 12 ft. sidewalk is 4ft by 12 ft.
If there is only one rectangular sidewalk with dimensions of 4 x 12 feet, you don't need subtraction to compute the area. The size of the "overall area" doesn't matter.
To find the area of the sidewalk, you need to subtract the area of the sidewalk from the overall area.
The overall area is given as 10 ft by 12 ft, which means that the area of the overall space is (10 ft) x (12 ft) = 120 square feet.
The sidewalk has dimensions of 4 ft by 12 ft, so its area is (4 ft) x (12 ft) = 48 square feet.
To find the area of the remaining space (sidewalk excluded), you subtract the area of the sidewalk from the overall area:
120 square feet - 48 square feet = 72 square feet.
Hence, the expression for the area of the sidewalk, using subtraction, is: 120 sq ft - 48 sq ft = 72 sq ft.