Let's start out with what we do know:
We have a 5.2L pitcher and 0.4L glasses and we want to know how many glasses we can fill with the 5.2L pitcher of water.
To answer that, we need to divide 5.2L by 0.4L in order to get the number of glasses (the number of 0.4L glasses that can go into a 5.2L pitcher)
So our equation will look like this:

where n = number of glasses
so by doing that division we get:

Notice that the L's cancel out leaving us with a plain number.
So a 5.2L pitcher of water can fill up
13 glasses!
Vertex is (4,0)
Fhats all I know
Since A is (-7,-4) and C is (7,3) for the x value from a to c is 14 for the y value from a to c is 7
Do 14 x 2/7 which is 4
Do 7 x 2/7 which is 2
then add (-7+4,-4+2) which is (-3,-2)