X=5 y=15 (5,15).
This is how you do it:
-4(2x+3y=55): -8x-12y=-220
3(9x+4y=105):27x+12y=315
You add the two new equations together, canceling out the y values, and get the x value. Then, you go back and plug in the x value in the original equation to get the y value.
Answer:
10. 23
11. -17
12. 0
13. -4
14. -6
15. 4
Explanation:
10. 8+15= 23
11. -8-9= -17
12. 8-8= 0
13. -8+4= -4 (same as 4-8)
14. -10+4= -6 (same as 4-10)
15. 12-8= 4
