Mrs. martin wants to place a ribbon around the outer edge of a rectangular mirror. the area of the mirror is 324 square inches. the width is of the mirror is 12 inches. how many inches of ribbon does mrs. martin need?

The inches of ribbon that Mrs. Martin needs will be equal to the perimeter of the rectangular mirror.

We know that the area of a rectangle equals the length times the width.

Area = length * width
324 square inches = length * 12 inches
length = 27 inches

The perimeter of a rectangle is two times the length plus two times the width.

Perimeter = length + length + width + width
Perimeter = 27 + 27 + 12 + 12 
Perimeter = 54 + 24 
Perimeter = 78 inches

Therefore, Mrs. Martin needs 78 inches of ribbon.