Write an equation system based on the problem Let w be the width of the rectangle, and l be the length of the rectangle 72 inches represents the perimeter of the rectangle, the equation will be ∴ 2l + 2w = 72 The length is three times of the width, the equation will be ∴ l = 3w
Solve the equation by substitution method. Substitute in 3w as l. 2l + 2w = 72 2(3w) + 2w = 72 6w + 2w = 72 8w = 72 w = 72/8 w = 9 The width of the rectangle is 9 inches
Find the length by subtitution of 9 as w l = 3w l = 3(9) l = 27 The length of the rectangle is 27 inches
