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

We are given:

(x/(x+y))(10) + (y/(x+y))(20) = k

[10x/(x+y)] +[20y/(x+y)] = k

We can combine the two fractions on the left side of the equation because they have the same denominator, (x + y).

[(10x + 20y)/(x+y)] = k

We see that we have a weighted average equation in which x items have an average of 10, and another y items have an
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