How do I substitut 3x+y=2, 4×+y=20?

2 Answers
Feb 24, 2018

(x,y)=(18, -52)

Explanation:

3x+y=2 => y=2-3x
4x+y=20
4x+2-3x=20
x=18
y=2-54=-52
(x,y)=(18, -52)

Feb 24, 2018

y=-52
x=18

Explanation:

Since y is a constant in both equations, you can shift 3x in 3x+y=2, so y=2-3x.
Then you can just substitute into 4x+y=20
So 4x+(2-3x)=20
x+2=20
x=18
Then substitute into any equation x=18
Substituting into first equation,
y=2-3(18)
y=-52