ABCD is a rectangle.
E is a point on CD so that the area of the triangle BCE is 15.
F is a point on DA so that the area of the triangle EDF is 12.
The area of the triangle FAB is 27.
Calculate the area of the triangle FBE.
If you had uploaded the picture of the rectangle, then I would give details of the solution. Since you haven't, this is all you will get:
The width of the recatngle=5
The length of the rectangle =18
Area of the rectangle=5 x 18 ==90 u^2
The areas of the 3 given triangles = 12 + 15 + 27 =54 u^2
Therefore, the area of triangle FBE = 90 - 54 =36 u^2