The given trapezoid has a line of symmetry that is at the midpoint of the base of the tapezoid.
Given that the base of the trapezoid runs from point (-3, 2) to point (7, 2), the midpoint is given by (-3 + 7) / 2 = 4 / 2 = 2.
Thus, the line of refrection the maps the trapezoid onto itself is x = 2.
