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Question

(x/x+y)*10+(y/x+y)*20=K
and if y>x, what could be the value of K?

the answer is 18, can someone show their steps?

thanks

Damager · Answer

(x/x+y)*10+(y/x+y)*20=K
and if y>x, what could be the value of K?

the answer is 18, can someone show their steps?

Using substitution

x=1 y=2
(1*10)/(3)+ (2*20)/(3)=50/3 not integer

x=1 y = 4 

(1*10)/5+ (4*20)/5= 90/5=18

keeeeeekse · Answer

thanks

that's how i did it as well

any faster way?

sujayb · Answer

I did it this way:

stem can be reduced to:

10 + 10y/ (x + y) = K

Now considering 10y/ (x + y) only ,

let 10y/ (x + y) = C (a constant)

y = x( 10 - C) / C
if C =1 and x = 1, y = 9
if C = 2 and x = 1, y = 4

Substituting each in the reduced equation,

K = 19, 18

MBAlad · Answer

How did you reduce it to that?

dred · Answer

Look at this scenario...

y>x, 3>2

10x + 20y = k(x+y)

10x2 + 20x3 = k (5)

Here k = 80/5 = 16.

y>x , 4>1 

Here k = 90/5 = 18.

Am I missing something. Is there a better way to solve this...so substitution might not really work out.

josh478 · Answer

Even more simple:

if x=2 and y=2
 1/2*10 + 1/2*20=k

k=15

answer choices would make the difference

sujayb · Answer

10x/(x+y) + 20y/(x + y) = K

or, 10x/(x + y) + 10y/(x + y) + 10y/(x + y) = K

or, 10(x + y)/(x+y) + 10y/(x+y) = K

or 10 + 10y/(x+y) = K

hth

sujayb · Answer

y is > x <img src="{SMILIES_PATH}/1f642.png" class="forumSmileyItem" width="20" height="20" alt=":)" title="Smile" />

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