You have 3 unknowns but only two equations,
so you can't "solve" for a unique solution.
Solve the following system of equations.
x1 + 2x2 + 6x3 = 8
x1 + x2 + 3x3 = 4
1 answer
x1 + 2x2 + 6x3 = 8
x1 + x2 + 3x3 = 4
1 answer