All you have to do is find the area of the individual shapes of each shape.
Triangle area = 1/2bh
Square area = bh
In shape a, 7 4/5 x 9 = 70.2 /2 = 35.1.
35.1 is the surface area of the triangle, which we multiply by 4 to get the total surface area, since there are 4 triangles.
The total surface area of shape a = 140.4
In shape b, 14 3/4 x 12 = 177 /2 = 88.5
88.5 being the surface area of one triangle, multiply by 4, to get the total area of all the triangles, 354.
However, we also need to add the square, which is 12 x 12 = 144.
144 + 354 = 498
The total surface area of shape b = 498
