Answer: 16
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Explanation:
The base of the bridge is the lower horizontal segment.
The trapezoid is a combination of a rectangle sandwiched by 2 right triangles. Each triangle is congruent to one another.
The triangles are 45-45-90 triangles indicating "45 degrees 45 degrees 90 degrees" are the three angle measures. Because of this, the legs are congruent. One of the legs is 4, so the other leg must be 4.
The shorter base of the trapezoid is added onto the two horizontal triangular legs to get 8+4+4 = 16
See the attached image to see a further breakdown of the trapezoid
