Each side of the pyramid as a base of 6 inches and height of 15 inches.
The area of a triangle is 1/2 x base x height:
Area = 1/2 x 6 x 15 = 45 square inches.
There are 3 sides: 45 x 3 = 135 square inches.
The base of the pyramid is 1/2 x 6 x 5.2 = 15.6 square inches.
Total surface are including the base = 135 + 15.6 = 150.6 square inches.