118k views
2 votes
Use addition or substitution to find the value of y for this set of equations. 4x + 13y = 40 4x + 3y = -40

User Toom
by
7.8k points

1 Answer

4 votes
4x + 13y = 40
4x + 3y = -40

multiply second equation by -1

4x + 13y = 40
-4x - 3y = 40

add equations together

10y = 80
y = 8

put y in either original equation

4x + 3(8) = -40
4x + 24 = -40

subtract 24 from both sides

4x = 64

x=16
y=8
User Adem ?Lhan
by
6.5k points