This may be one that is more easily worked with numbers than algebra for some people.
is m/r = x/y? all numbers are positive and we are working within ratios
1) if m = 2, y = 3, x = 4 and r = 6 then 2/3 = 4/6 BUT 4/3 does not equal 2/6
However all the numbers could be the same - if they are all 2 then 2/2 = 2/2
thus, we do not always know whether the ratio will be the same and the answer is BCE.
2) if you pick x = 2 and y = 3 then in order to make m+x/r+y = 2/3 you have to pick multiples of each x and y for m and r - m must be 4 and r is 6 or , m is 8 and r is 12
working a little with the numbers shows you that statement 2 is sufficient.
Becky
Master GMAT Instructor
The Princeton Review
Irvine, CA