Answer:
8x+10y
Step-by-step explanation:
What you do first is you need to subtract -2y from 9y to get 7y.
So you have (12x+7y)-(4x-3y). The negative sign needs to be added into the problem so it will be (12x+7y)+(-4x+3y). You will then add and minus them together to get 8x+10y.
Well divide them. 2/3=0.666 repeated. So use a bar over the top of the third six.
Answer:
Step-by-step explanation:

First let's multiply the 1st equation by 10.

So, we can see that the equations have the same coefficients and that implies they are equal.
So the equation has no solutions for. 
the problem is a pattern that multiplies by two and subtracts one each time.
3x2=6 6-1=5 5x2=10 10-2=9 9x2=18 18-1=17 17x2=34 34-1=33