In a right rectangles pyramid with base edges a= 18 cm and b= 10 cm the slant height toward a is k= 13 cm while the slant height towards b is l= 15 cm. what is the surface area of the pyramid

To find the surface area of the pyramid, you will need to find the areas of all 5 faces.

rectangular base:
A = lw
    18 x 10
A = 180 square cm

side a triangular lateral faces:
A = 1/2bh
      1/2 x 18 x 13
A = 117 square cm x 2= 234 square cm

side b triangular lateral faces:
A = 1/2bh
      1/2 x 10 x 15
A = 75 square cm x 2= 150 square cm

Add all the bold areas together:
150 + 234 +180 = 564

The surface area is 564 square cm.