What is the solution of this system?
x+y+z=2
2x-y-z=7
3x+2y+z=6
You can use elimination to solve this one, but the coefficients are ideal for a substitution.
Add the first two equation, you will end up with 3x=9, or x=3.
substitute x into the second & third equations and add, you will get y=-2.
Substitute x=3 and y=-2 into the third equation to get z=1.
Do a back substitution to check the answers.