Answer:
216cm^2
Explanation:
The surface area is equal to the sum of areas of the walls.
We've got 2 triangular walls with area 6*8/2, for 6*8 = 48cm^2 total
We've got a wall with 7x10 = 70cm^2
We've got a wall with 6x7 = 42cm^2
And the last wall is 8x7 = 56cm^2
So total surface area is: 48 + 70 + 42 + 56 = 216