GMAT Problem Solving (PS) | Re: If x, y, and k are positive numbers such that (x/(x+y))(10)

I used VeritasPrepKarishma's method. This is the basic formula for weighted average.

Since it is 10x + 20y/x+y then k has to fall between 10 and 20. And since x < y then its closer to 20. Hence 18.

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