Answer:
The answer is D or (10,-9)
Explanation:
Since y is already given (and you have to use the substitution method) substitute y into one of the equations. So you should have something like this:
-2x+11=3x+21
After that merely solve for x which should get you x=10. After you get your x value plug 10 in either (of the original) equation and your y value should be -9. For example if you chose y=-2x+11 you should have y= -2(10)+11. In the end your answer should be (10,-9).
If you want to check your work merely plug your answer into both equations (ex: -9=-2(10)+11 --> -9=-9), therefore you know your answer is correct).
Hope this helped!