Area of a Trapezium
The trapezium has two parallel sides and two non-parallel sides
Since sides of lengths 7, 5 are parallel and perpendicular to the side of length 4. Thus the trapezium has bases b1=7, b2=5, and height h=4.
The formula to calculate the area of a trapezium is:

Substituting:

The area of the shaded region is 24 square units