The perimeter of the base of the regular quadrilateral pyramid is P = 30 cm. Find the sum of all edges of this pyramid, if the perimeter of a lateral face is 27.5 cm

The perimeters of two opposite triangular faces includes all 4 slant edges and 2 of 4 base edges. The other two base edges are half the base perimeter, so the total length of all edges is

... 2 * (27.5 cm) + (1/2) * (30 cm) = 70 cm