SOLUTION: x+y=12 x-7=4 how do u go about solving a question like this??

Question 173215This question is from textbook Amsco's integrated algerbra 1
: x+y=12
x-7=4

how do u go about solving a question like this?? This question is from textbook Amsco's integrated algerbra 1

Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Note: I'm assuming that you left out the variable "y" in the second equation and it should look like

Start with the given system of equations:

Let's solve this system by use of substitution

Now in order to solve this system by using substitution, we need to solve (or isolate) one variable. I'm going to solve for y.

So let's isolate y in the first equation

Start with the first equation

Subtract from both sides

Rearrange the equation

---------------------

Since , we can now replace each in the second equation with to solve for

Plug in into the second equation. In other words, replace each with . Notice we've eliminated the variables. So we now have a simple equation with one unknown.

Distribute to

Multiply

Combine like terms on the left side

Add 84 to both sides

Combine like terms on the right side

Divide both sides by 8 to isolate x

Divide

-----------------First Answer------------------------------

So the first part of our answer is:

Since we know that we can plug it into the equation (remember we previously solved for in the first equation).

Start with the equation where was previously isolated.

Plug in

Multiply

Combine like terms

-----------------Second Answer------------------------------

So the second part of our answer is:

-----------------Summary------------------------------

So the solutions are:

and

which form the ordered pair

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