Triangles ADE and CDF are similar, so:-
10/12 = 15/CD
CD = (12*15) / 10 = 18 cm = AB = base of the parallelogram
Area of the parallelogram = base * height = 18 *10 = 180 cm^2 (answer)
(b) The perimeter:-
AD = CB = 15 (opposite sides are equal)
Perimeter = 2*18 + 2*15 = 36 + 30 = 66 cm (answer)