SOLUTION: To Whomever can assist, Thank you! This question has to do with the substitution method. I'm not sure how to do this. x + y = 20 x = y - 4

Algebra ->  Linear-equations -> SOLUTION: To Whomever can assist, Thank you! This question has to do with the substitution method. I'm not sure how to do this. x + y = 20 x = y - 4      Log On


   

Question 60132This question is from textbook Elementary and Intermediate Algebra
: To Whomever can assist, Thank you!
This question has to do with the substitution method.
I'm not sure how to do this.
x + y = 20
x = y - 4 This question is from textbook Elementary and Intermediate Algebra

Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Solving systems of equations by substitution is just one of the ways to handle this type of problem.
The idea is to reduce the number of variables (unknowns) from (in this case) two to one by substituting one of the variables by an equivalent expression that contains the other variable. Here's how it goes:
x + y = 20
x = y - 4 Substitute this equation for x into the first equation.
(y - 4) + y = 20 Simplify and solve for y.
2y - 4 = 20 Add 4 to both sides.
2y = 24 Divide both sides by 2.
y = 12 Now substitute this equation for y into either of the two given equations and solve for x.
x + (12) = 20 Subtract 12 from both sides.
x = 8
The solution is: (8, 12)