shibal wrote:2 more....

I´m not very sure how to explain this.
But try numbers Ej. x+y could be 4,5 or 3,5 and x-y could be 0,5 or 1,5. Multiples values for x and for y, so to know this we will need multiple equations, besides x can be positive and y negative or viceversa. Also the addition or subtraction of both numbers could give an integer or a not integer.

It ´s interesting to know how you reach answer C or you were just guessing?

for # 2 given that

mv<pv<0

so if v>0, p<0, and m<0 and m<p

if v<0, p>0, m>0

1 m<p means that v>0 try values of v=1 p=-2 then m<-2 to make the inequality work

SUFF

2 m<0

IF M<0 v>0 for inequality to work

Suff

D