Question

Solve the system of equations by substitution. Write your solution as an ordered pair

4x+8y=20
x=3y-20

Answer 1

Solving it by substitution is:

4(3y-20)+8y=20: substitute the second equation into the first equation (hence the name solving by substitution)
12y-80+8y=20: distribute 4 to 3y and 4 to 20
20y-80=20: combine like terms (12y+8y)
20y=100: add 80 to 20
y=5: divide 100 by 20 and you get 5

:)

Answer 2

Answer: (-5,5)

Step-by-step explanation:

graphing the two equations on a calculator gets the point (-5,5)