The sum of the perimeters of an equilateral triangle and a rectangle is 90 cm the area, T, of the triangle and the area, R, of the rectangle, both in sq cm, satisfy the relationship R = T2. If the sides of the rectangle are in the ratio 1 ∶ 3, then the length, in cm, of the longer side of the rectangle, is

• A. 21
• B. 18
• C. 24
• D. 27