4a=20⇒a=5
we know diagonals are perpendicular. if u look at one of the right triangles, you can see that for hypotenuse to be 5, the legs have to be 4 and 3 to satisfy the given ratio 4:3.
so, diagonals are 8 and 6 as we know that diagonals bisect each other.
Area=8*6/2=24