To find the surface area of this figure, we simply have to add up the individual areas of the shapes that make up the figure.
Surface area = 4(area of triangle) + area of square
Surface area = 4 ( 1/2 * base * height) + side^2
Surface area = 4( 1/2 * 6 * 7) + 6^2
Surface area = 4 (3 * 7) + 36
Surface area = 4(21) + 36
Surface area = 84 + 36
Surface area = 120 cm^2
Hope this helps!