The pyramid shown has a square base that is 14 centimeters on each side. the slant height is 15 centimeters. what is the surface area of the pyramid?

We know that

surface area=area of the base+4*[area of one lateral triangle side]

area of the base=b²
b is the side length of the square
b=14 cm
area of the base=14²> 196 cm²

area of one lateral triangle side=b*h/2
b is the side length of the square
b=14 cm
h is the height of the lateral triangle side
h is equal to the slant height 
h=15 cm

area of one lateral triangle side=14*15/2> 105 cm²

surface area=196+4*[105]> 616 cm²

the answer is
the surface area is 616 cm²