SOLUTION: if 6x-3y=30 and 4x=2-y then find x+y.

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: if 6x-3y=30 and 4x=2-y then find x+y.      Log On


   

Question 30571: if 6x-3y=30 and 4x=2-y then find x+y.
Answer by Cintchr(481) About Me  (Show Source):
You can put this solution on YOUR website!
+6x-3y=30+ and +4x=2-y+ then find x+y
get the second equation in y=mx+b format
+4x=2-y+ add y to both sides
+4x%2By=2+ subtract 4x from both sides
+y=-4x%2B2+ Plug this into the first equation
+6x-3%28-4x%2B2%29=30+ distribute the -3
+6x%2B12x-6=30+ Add 6 to both sides
+6x%2B12x=30%2B6+ Combine like terms
+18x=36+ divide by 18
+x+=+2+
Plug this back into the second equation
+4%282%29=2-y+
+8=2-y+ subtract 2 from both sides
+6+=+-y+ negative variables is a no no .... change all the signs
+-6+=+y+
Plug x and y into x+y
+x%2By+
2%2B-6
-4