Thread: Substitution

It's been awhile since i've done substitution and the notes i've taken seem to make no sense to me. I have a big unit test on Wednesday and am in need of help.

How would I solve this equation in substitution?

x + y = 27
y = 3x +7

I've tried to do this equation numerous times but am unable to do it.

Any help please?

Originally Posted by largebabies

It's been awhile since i've done substitution and the notes i've taken seem to make no sense to me. I have a big unit test on Wednesday and am in need of help.

How would I solve this equation in substitution?

x + y = 27
y = 3x +7

I've tried to do this equation numerous times but am unable to do it.

Any help please?

plug the second equation into the first (substitute the expression for y), you get

x + (3x + 7) = 27

nw solve for x. when done, solve for y by plugging in your x-value in either equation