I can't answer all of these for you but I will give you insight on how to complete them on your own.
Item 2:
Calcuate the surface area for each side of the box.
5ft by 6ft by 7ft
There are two sides with 5 x 6, two with 5 x 7, and two with 6 x 7.
Calcuate the area of each side and add them up.
Then check which paint bucket is the right one.
Total Surface Area = Paint Can
Item 3:
Do the same exact thing as stated in item two. Find the surface area of each side and add them all together.
Item 4:
Do the same exact thing as stated in item two. Find the surface area of each side and add them all together.
Item 5:
Use this equation:
1 * base * length * height
-------------------------------------------
2
Then you will get your solution cubed.
Hope this helps :D