My usual policy of not giving complete answers where I can is in effect.
A curious choice of labels for that first one -- were it an engineering drawing it would probably be called over constrained, however if they don't want you to have to calculate another I guess it plays.
Anyway there are a variety of approaches but imagining it as a cuboid is probably not of much use here, at least not in full -- no sense making life hard if you have two identical right angle triangles you can imagine as a square and just do 6x9.
Other than that it is just plain areas of a square and adding it all up, ignoring the base when it asks you about the lateral area. Bonus is the differences between the two values in the multiple choice there are different so in a hurry or as a check you could see the base area, figure out the differences and then check it. Sometimes the test maker might have messed up and left only one right answer.
You have to figure out the area of each face and add them together, or in the case of lateral area then leave out the base area (seems a pointless thing to teach but that is not why we are here).
2) pi x radius squared is the area of a circle.
pi x diameter is the circumference, which also happens to be the edge of the quadrilateral you get if you unwrap it. The length/height of the cylinder is the other measurement for that quadrilateral. Bonus is they are the same so it is actually 12X12Xpi + the circle end caps
Choice video
3) There are a couple of ways to look at this. The way I would use though as you have a simplified problem in this case
lsa = pi x radius x slant height
You know lsa and you know radius, pi is a number so you now need to solve for slant height.
Do note that you have 500xpi as the area, the typography on your work sheet is bad though so be careful. It does also mean pi cancels out of the equation when you are rearranging it.