To find a line of reflection that will flip the trapezoid PQRS onto itself, we can look for lines that will symmetrically divide the trapezoid.
Looking at the coordinates of the points:
- P (-3, 2)
- Q (3, -1)
- R (3, -4)
- S (-3, -7)
The trapezoid has vertical symmetry because points P and S are symmetric with respect to the y-axis, as are points Q and R. Therefore, the line of reflection that would flip the trapezoid onto itself is the y-axis.
Thus, the answer is: y = 0
(Assuming you meant the vertical axis; if the answer is for a different reference, e.g., other suggested lines, you might mean the line y = -2 (the midpoint between the highest and the lowest point). However, y = 0 typically is considered the most symmetric.)