area of the triangle is 1/2 ( b * h) so
1/2 (12 * 14)
12 *14 = 168 then 168 * 1/2 = 84 so the area of the full triangle is 84cm but to get just the shaded area subtract the full triangle area and the squares area.
area of a square is ( b * h ) so 3.5 * 3.5 = 12.25
so the triangles area is 84 cm - 12.25 = 71.75
answer is D 71.75 cm