The correct answer is 50 cm or 500 mm. There are 4 base edges and 4 lateral edges, so just multiply the number for both edges by 4 and add. The question threw a curveball at us by giving us two units of measurement, millimeters and centimeters, but since we know that there are 10 millimeters in a centimeter, we can just divide 55 by 10 to get 5.5.
5.5 x 4 = 22 7 x 4 = 28 28 + 22 = 50
If it helps, you can draw the figure and label the edges. Remember that the lateral edge of a quadrilateral pyramid is the slanted line leading up to the top of the pyramid, and that the base edges are the sides of the quadrilateral on the bottom.
