Trying to apply matrices in Physics but having trouble

__Here is the original matrix:__

matrix([20,10,0,0,549/100],[0,-10,30,30,41/50],[20,0,30,30,467/100],[1,-1,-1,0,0])

__Here is the matrix in its echelon form:__

matrix([1,1/2,0,0,549/2000],[0,1,2/3,0,183/1000],[0,0,1,9/11,303/11000],[0,0,0,0,1])

(The last column is for the constants on the right of the augmented line of the matrix).

Sorry for the dumb question but can someone please help me extrapolate the values of x1, x2, x3, and x4 given this information?

Any help would be greatly appreciated!

Thanks in advance!