elimination method
a+7b=13
a+2b=-2

Question

elimination method 
a+7b=13
a+2b=-2

anonymous · Answer

7b-2b = 13-(-2) 
5b = 15
b = 3

anonymous · Answer

a + 7(3) = 13
a + 21 = 13
a = 13-21
a=-8

anonymous · Answer

So the one solution is? 3,-8?

anonymous · Answer

$$a+7b=13[1]$$
$$a+2b=-2[2]$$
$$[1]-[2]$$
$$(a+7b)-(a+2b)=(13)-(-2)$$
$$a+7b-a-2b=13--2$$
$$5b=13+2$$
$$5b=15$$
$$b=3$$
Find a by subbing b as 3 into one of the equations given to you above.

anonymous · Answer

Make sure you don't just seek for the answers. Actually look at how people solve the questions. Look at their methods and their approach to the question. You will better understand how to solve these if there comes a time for an exam.

anonymous · Answer

Definitely.  I am trying to better understand the entire concept

anonymous · Answer

since the point is finding a and b then the answer is an ordered pair starting with a correct?

anonymous · Answer

Could you rephrase that last part please? ordered pair starting with a?

anonymous · Answer

a is 3 so it is 3,-8

anonymous · Answer

thanks

anonymous · Answer

no it's not 3.

anonymous · Answer

You mixed it up.

anonymous · Answer

I meant te othe way around sorry,  -8,3)

anonymous · Answer

3=b