SOLUTION: I am studying for my 8th grade algebra final and i dont understand the way that on this linear system 4x+5y = 7 6x-2y = -18 how do i do this

Question 2754: I am studying for my 8th grade algebra final and i dont understand the way that on this linear system 4x+5y = 7
6x-2y = -18
how do i do this x = (7 -5y)/4
Substituting this expression into the second equation:
6(7+5y)/4-2y = -18

and from after that how do i simplify this 6(7+5y)/4-2y = -18
into this (-38)y = -114
I listen in class but i was absent on some very important days and this doesnt make sence
I thank anyone who could help.

GOD BLESS YOU ALL
Answer by longjonsilver(2297) (Show Source): You can put this solution on YOUR website!
this is correct, well done.

this is not correct as you have +5y..it should be -5y. I guess this was just a simple typo error?.

anyway, correct version is:

First multiply every term by 4:
so that the fraction in the first term cancels itself:

y = 3

Now sub this back into eiter equation - pick the one that looks the easiest! I pick the first equation:

4x+5y = 7 becomes ...

DEFINITELY put these answers in the second equation, to make sure that they equal to -18...

becomes

so the answer is DEFINITELY correct.

jon

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