Solved by gauss elimination

Question

3x+4y+5z=18
2x-y+8z=13
5x-2y+7x=20

Answer 1

There is an excellent G-J calculator here:

http://www.gregthatcher.com/Mathematics/GaussJordan.aspx

You can set the size of the matrix and enter the coefficients. Then it will show all the intermediate steps of the solution.

Answer 2

@Steve, that calculator doesn't work anymore