400+429=829 ..........mma
The surface area would be 150cm and the volume would be 125cm. To get volume you do 5 cubed to get the answer 125. To get surface area you would do 5 multiplied by 5 multiplied by the cubes 6 sides to get 150.
8.5, you follow a^2+b^2=c^2 since it is a right triangle