You need to determine how much paper you need to cover the lateral side of the cylinder shown in the picture. For this, you have to calculate the surface area of the cylinder, which you can do using the following formula:

Where
A is the area
π is the number pi, for the calculations we usually use up to the first two decimal values of this number, 3.14
r is the radius
h is the height of the cylinder
The given cylinder has a height of h=15m and a diameter of d=6m
To calculate the lateral area you need to use the radius. The diameter is twice the radius, so to determine the radius of the cylinder you have to divide the diameter by 2

Now you can calculate the lateral area as follows:

Charlie will need 282.6 m² to cover the lateral side of the cylinder.
53.8516 if you are use the Pythagorean theory. You create a triangle making the longest line the C.
Inverse variation equations take the following form:
y = a/x, where a is some constant
We know x=3, y=16 and x=6, y=8 satisfy the equation.
Let's find the value of a.
16=a/3
Multiply both sides by 3
16*3 = a
48 = a
Thus, the equation is:
y = 48/x
You can use the other values of x and y to test, but I'm sure this is the correct equation. :)
(This answer was sent on mobile, so please pardon any spelling errors I may have)