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If \(888x + 889y = 890\) and \(891x + 892y = 893\), what is the value of \(x-y\) ?

tertre  Dec 28, 2017
 #1
avatar+87293 
+1

888x   +  889y  =   890

891x   +  892y  =   893

 

Subtract  the  first equation from the second

 

3x  + 3y   =  3

x +  y   =  1       ⇒   y =  1 - x

 

So....using the first equation

 

888x  +  889 (1 - x)  =  890

888x  +  889  -  889x  =  890

-x  =  1

x  =  - 1

 

So.....   y  =  1 - (-1)  =    2

 

So

 

x  -  y   =    -1  -  2   =    -3

 

 

cool cool cool

CPhill  Dec 28, 2017
 #2
avatar+493 
+1

very nice solution, CPhill!

ant101  Dec 28, 2017
 #3
avatar+87293 
+1

Thanks, ant!!!!

 

 

cool cool cool

CPhill  Dec 28, 2017

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