+0  
 
+1
5
2
avatar+86 

If x and y are positive integers for which \(3x + 2y + xy = 115 + 7x + 6y\), then what is x + y?

 May 14, 2024
 #1
avatar+129514 
+1

Rearrange as

 

4x + 4y - xy + 115  =  0

 

4y - xy  =  -4x - 115     multiply through by -1

 

xy - 4y  = 4x + 115

 

y [ x - 4]  =  [ 115 + 4x ] 

 

y  =  [ 115 + 4x  ] / [ x - 4]

 

Note that when  x = 5,   y =  135

 

x + y =   5 + 135  =   140

 

cool cool cool

 May 14, 2024
 #2
avatar+86 
+1

Thanks CPhill!

eramsby1010  May 14, 2024

7 Online Users

avatar
avatar
avatar
avatar
avatar
avatar