125
Step-by-step explanation:
Surface area is the total area of all the surfaces of a shape. In order to calculate the surface area we need to consider each unique face individually.
The base of the pyramid is a square of side-length 5, and its area is 5×5=25
The side faces form an iscosoles triangle of height 10 and base length 5, its area is 10×5×=25.
The total surface area = Triangle +Triangle +Triangle +Triangle +Square = 25+25+25+25+25 = 125
