For volume, the formula is length*width*height, for example, in (c), we have the length, 3, multiplied by the width, 6, multiplied by 2 (which is the height). This gives us 36 cm^3 as our answer.
For surface area, you find the area of each side, then add the areas up. In (c), we have two sides with 6*3 as the area, two sides with 6*2 as the area, abd 2 sides with 3*2 as our area. This gives us (6*3)+(6*3)+(6*2)+(6*2)+(3*2)+(3*2) = 72 cm^3 as the surface area.
You can do this with the rest of the rectangular prisms.
Hope this helped!
Caffeine :)