Calculate Trapezoid Area: Finding the Space of ABCD with Height 5

To solve this problem, we'll follow these steps:

• Step 1: Identify the lengths of the trapezoid's bases: $AB = 7$ and $CD = 9$.
• Step 2: Identify the height of the trapezoid: $AD = 5$.
• Step 3: Apply the trapezoid area formula: $A = \frac{1}{2} \times (b_1 + b_2) \times h$.
• Step 4: Calculate the area using the values from Steps 1 and 2.

Now, let us work through each step:
Step 1: The length of base $AB$ is $(b_1 = 7)$ units, and the length of base $CD$ is $(b_2 = 9)$ units.
Step 2: The height $AD$ is $(h = 5)$ units.

Step 3: Substitute the known values into the formula for the area of a trapezoid:
$A = \frac{1}{2} \times (7 + 9) \times 5$

Step 4: Calculate the results:
$A = \frac{1}{2} \times 16 \times 5 = \frac{1}{2} \times 80 = 40$

Therefore, the area of trapezoid ABCD is $\mathbf{40}$ square units.