If m/n = 5/3, what is the value of m + n ?

From S1:m>0
m and n could take diff positive values like (5,3) or (25,15).Accordingly,value of m+n will change.Insufficient.
From S2:2m+n=26
As m=5n/3,replacing in the above equation,we get (10n/3)+n=26=>13n/3=26
n=6 and m=10.Therefore,m+n=16.Sufficient.
Ans.B

Question stem says 3m=5n.

Statement (1). m>0 gives multiple values of m+n. Insufficient

Statement (2). 2m+n=26. This is sufficient when combined with the relationship of m and n in the stem.

Answer B

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If m/n = 5/3, what is the value of m + n ?

(1) m > 0
(2) 2m + n= 26

There are 2 variables (m,n), and one equation (m/n=5/3), and 2 more equations from the 2 conditions; there is high chance (D) will be our answer.
For condition 1, m>0. We cannot decide on a value, so this is insufficient
For condition 2, 2m+n=26, 3m=5n. We get m=10, n=6. This is sufficient, and the answer is (B).

For cases where we need 1 more equation, such as original conditions with “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 59 % chance that D is the answer, while A or B has 38% chance and C or E has 3% chance. Since D is most likely to be the answer using 1) and 2) separately according to DS definition. Obviously there may be cases where the answer is A, B, C or E.

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