How do you solve by substitution 4x + 6y = 62 4x+6y=62 and 10x - 2y = 210x2y=2?

1 Answer
Jun 5, 2015

10x-2y=210x2y=2
10x=2+2y10x=2+2y ( we add 2y2y on each side )
10x-2=2y10x2=2y ( we substract 22 on each side )
5x-1=y5x1=y ( we divide by 22 on each side )

Now that we have yy, we can use substitution in the first equation :

4x+6*(5x-1)=624x+6(5x1)=62
4x+30x-6=624x+30x6=62
34x-6=6234x6=62
34x=62+634x=62+6 ( we add 66 on each side )
34x=6834x=68
x=68/34=2x=6834=2 ( we divide by 3434 on each side )

Now that we have xx, we can find yy :

We know that y=5x-1y=5x1, as we calculated it before :

y=5*2-1=10-1=9y=521=101=9