Answer
The points of view are
(a) $(20,0,0)$
(b) $(-15,10,20)$
(c) $(20,15,25)$
(d) $(20,20,0)$
Work Step by Step
The point from which we look at the graph is determined by how the axes are oriented.
(a) Here notice that we see $y$ and $z$ axis only, and the origin is in the center of our view. This means that we are sitting somewhere on the $x$ axis and the fact that the origin is centered implies that $y=0$ and $z=0$ so the point of view is $(20,0,0)$.
(b) The $y$ and $z$ axes are directed towards us and the $x$ axis points away from us which says that $y$ and $z$ coordinates of our point of view are positive and the $x$ coordinate is negative so the point of view is $(-15,10,20)$.
(c) All three axes point towards us so all three coordinates are positive so the point of view is $(20,15,25)$.
(d) We see all three axes. $x$ and $y$ appear to be on the same line which is possible only if we are in the $xy$ plane where $z=0$. So our point of view is $(20,20,0)$.
