You can do it by making a matrix A of coefficients and a matrix b of the number on right side of the equations.
A = [column_of_coefficients_of_x1, column_of_coefficients_of_x2, ... column_of_coefficients_of_xn];
b = [column_of_values on RHS of the equations];
For the equations, you gave in the question,
A = [5 4 -2 6; ...
3 6 6 4.5];
b = [4; ...
10];
You can then solve the system using
A\b
