Volume is how much something can be filled. Surface area is the surrounding area of the object. For example; the surface area of a ballon is the rubber and the volume is the air or helium.
x is less than or equal to 12
(Distribute the 3 )
3x+3<39
(Move the 3 to the other side by subtracting)
3x<36
(Divide 3 on both sides)
x<12
*Note that I don't know how to do the less than or equal sign on my computer so please excuse that)
C. because u can't name a congruent triangle by angle angle angle