If all variables are positive, is (w/x) > (y/z)?
1) w = y + 50
2) x = z + 50
1) and 2) alone are INS.
(y+50)/(z+50) > y/z
yz +50z > yz +50y
50y > 50z
y > z
Both together are INSUFICIENT so E)
My question is, however: The first time that I worked it out, I simply did this...
If w = y + 50 , then w > y
If x = z + 50 , then x > z
Divide equations by each other:
(w > y) ÷ (x > z) = (w/x) > (x/z)
Why isn't this right?
You can't divide with relational operators as all the w,x,y,z are variable and +ve. They can be equal in pairs.
consider the simple example :
w= 1+50= 51
z = 1
So w/x = y/z
So doing a division operation in relational operator with variable is not so good appraoch where you dont know the range of the number.
+1 Kudos if you like and understand.