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.