Answer:
205.2
Explanation:
First get the area's of the 3 triangles on top of the base, the formula is base x height divided by 2
10 x 9 = 90
90 / 2 = 45
Multiply the area of the 3 sides together :
45 x 3 = 135
Now find the area of the base triangle :
9 x 7.8 = 70.2
To find the surface area of the ENTIRE shape you have to add all the sides :
135 + 70.2 = 205.2