Answer:
(C) 10
Explanation:
x+y−z=8
Subtract y from both sides
x-z= -y+8
Add z to both sides
x= -y+z+8
Subtract 8 from both sides
x-8= -y+z
x−y+z=12
Add y to both sides
x+z=12+y
Subtract z from both sides
x=y-z+12
Subtract 12 from both sides
x-12=y-z
Multiply both sides by -1
-x+12= -y+z
Combine equations:
x-8= -x+12
Add x to both sides
2x-8+12
Add 8 to both sides
2x=20
Divide both sides by 2
x=10
The answer is (C) 10.