18??
Re-arranging you will get (10X +20Y)/(X+Y) = 10 +10Y/(X+Y)
Now X+Y = 10
1,9
2,8
3,7
4,6
Only 2,8 matches the answer options
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1-17
Source: Beat The GMAT — Problem Solving |
Thanks - yes, OA is D.
sorry...but
can you show me the process from 10X+10Y/(x+y) to 10+10y/(x+y)???
from there how to get 18?
sorry...but
can you show me the process from 10X+10Y/(x+y) to 10+10y/(x+y)???
from there how to get 18?
[ Cut-n-paste from my earlier post ]dunkin77 wrote:Thanks - yes, OA is D.
sorry...but
can you show me the process from 10X+10Y/(x+y) to 10+10y/(x+y)???
from there how to get 18?
The eqn can be reduced to
(10x + 20y) / (x+y) = k
10 + 10y/(x+y) = k
y / (x+y) will be > 0 and < 1 as we know x and y are positive. So,
discard A and E.
When x = y, y/(x+y) = 1/2 and when x = 0, y/(x+y) = 1. So, value of
y/(x+y) will vary between 1/2 and 1. So, discard B and C.
Only D remains.

















