SOLUTION: Solving this linear equation with substitution. The linear equation is: 4x-5y=20 and 5x+5y=70. I need this solved by substitution and I must show all the work. Thanks

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: Solving this linear equation with substitution. The linear equation is: 4x-5y=20 and 5x+5y=70. I need this solved by substitution and I must show all the work. Thanks      Log On


   

Question 314937: Solving this linear equation with substitution.
The linear equation is:
4x-5y=20 and 5x+5y=70.
I need this solved by substitution and I must show all the work.
Thanks
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
1.4x-5y=20
2.5x%2B5y=70
From eq. 2,
5y=70-5x
Substitute this expression into eq. 1,
4x-%2870-5x%29=20
4x-70%2B5x=20
9x=90
highlight%28+x=10%29
Then,
5y=70-5x
5y=70-50
5y=20
highlight%28y=4%29