SOLUTION: i don't understand how substitution works. can anyone explain to me in a easy way?

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: i don't understand how substitution works. can anyone explain to me in a easy way?      Log On


   

Question 256989: i don't understand how substitution works. can anyone explain to me in a easy way?
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
Let's say you have two equations.
a+b=10
a+2b=16
solve the first one for a in terms of b
a=10-b
now plug 10-b in for a in the other equation
a+2b=16
(10-b)+2b =16
Do you see how I substituted 10-b for a because a=10-b?
Now we can solve the new equation and find out what b is.
10-b+2b=16
combine -b and +2b
-b+2b=b
so now we have 10+b=16
subtract 10 from both sides
b=6
but a+b=10
so a+6=10
a=4