Here, trapezoid is composed of two triangles, and one rectangle.
So, Area of rectangle = 4 * 7 = 28 cm²
Area of a triangle = 1/2 * 3 * 7 = 21/2 = 10.5 cm²
Area of Trapezoid = area of rectangle + 2(area of triangle)
= 28 + 2(10.5)
= 28 + 21 = 49
In short, Your Answer would be 49 cm²
Hope this helps!