Separate the kite into two triangles.
The base of the triangles would be 6 ( half the width is given as 3, so the full width would be 3 x 2 = 6).
The height of the bottom triangle is given as 10.
The area of a triangle is 1/2 x base x height.
Bottom triangle = 1/2 x 10 x 6 = 30 square units.
For the top triangle you need to find the height using the Pythagorean theorem.
Height = √(5^2 - 3^2) = √(25-9) = √16 = 4
Now the area of the top triangle is 1/2 x 4 x 6 = 12 square units.
Total area = Bottom + top = 30 + 12 = 42 square units.