charmingirl8 wrote:Can anyone help? The answer is C but i don't agree with it as for letter B one of the numbers could be negative but lower than the positive number so the sum will be positive...does it make sense?

ARE THE INTEGERS Z AND F TO THE RIGHT OF 0 ON THE NUMBER LINE?

1- THE PRODUCT OF Z AND F IS POSITIVE
2- THE SUM OF Z AND F IS POSITIVE

THANKS EVERYONE!

From 1 they could either be both positive or both negative.
From 2 both could be positive or one of the numbers could be negative but lower than the positive number so the sum will be positive so cannot be said.

Therefore combining both
Both have to be positive.

Hence C

Given :
Q- Y-N;
is Z,F < 0;

1. Z * F = +Ve ==
(Z,F) = ( +v,+v) : No
(Z,F) = (-v , -v ) : Yes
Insufficient:

2.Z+F = +v
Z,F = (+v,+v) : No
Z > F ( +v,-v ) : F <0, Z<0 :
Insufficient:

1+2:
from 1 ; It (Z,F) has to (-ve,-ve) or (+v,v)
from 2 : (Z,F) (+v,+v)
Hence : (Z,F) = (+v,+v) : Z,F >0 : No

C: Sufficientg