I think this question is incorrectly posted
1) x-y=z
this is not possible since the figure is a rectangle & the sides are x ,y & the diagonal z
so the the diagonal is the hypotenuse (pythagoras side opposite to 90 deg)
hence z > x & z >y
so x-y = z is not possible
and ofcourse 2) z =13 is insuffucient
if this data is correct then ans is E as we cannot use the first statment in any way.
