x - unit of length
w,l - the sides of a rectangle
7 : 2 ⇒ 7x : 2x
Perimeter: P = 207cm
Perimeter: P = 2w + 2l
therefore: 2w + 2l = 207 |divide both sides by 2
w + l = 103.5 (cm)
w : l = 7 : 2 ⇒ w : l = 7x : 2x ⇒ w = 7x; l = 2x
subtitute
7x + 2x = 103.5
9x = 103.5 |divide both sides by 9
x = 11.5 (cm)
7x = 7 · 11.5cm = 80.5cm
2x = 2 · 11.5cm = 23cm
w = 80.5cm; l = 23cm
Area = wl
Area: A = 80.5cm · 23cm = 1851.5cm²