Assuming 15 is the length of the "roof" of the trapezoid and 23 is the length of the entire base of the trapezoid:
ANSWER
171 square units
Step-by-step explanation
The area of a trapezoid is given by
Area = 1/2(a+b)(h)
where a and b are the lengths of the "roof" and the base (order of addition does not matter) and h is the height of the trapezoid.
Therefore,
Area = 1/2(15 + 23)(9) = 171
The area of this trapezoid is 171 square units.