Soln
= (x/x+y)10+(y/x+y)(20)
= 10(x/x+y)+10(y/x+y)+10(y/x+y)
= 10(x+y)/(x+y) + 10(y/x+y)
= 10 + 10 (y/x+y)
since x and y are positive so
the answer will certainly be greater than 10
A is out
since y > x
so y/(x+y) will always be greater than 1/2
had y been equal to x, the value could have been equal to 1/2
so 12 and 15 are also out
Now we are left with 18 and 30
y/(x+y) will always be less than 1
it can never be greater
so 30 is out
we are left with 18, the answer
You will not require this much effort evrytime, once you are through with the concept, by looking at statement you will be able to judge
that result is between 15 and 20 [non inclusive]
Also,
No offenses but I personally dont like number substitution.
If you want to do with substitution, you can do so
choose any set of numbers and solve
than take another set and solve
you will find the result to be between 15 - 20
and
if u r fortunate you may get 1 and 4 as your first choice and 18 as answer.
Hope this helps!!!
vivek.kapoor83 wrote:howcm u arrived at x=1 and y=4.pls explain
