||'''Book'''|| Advanced Engineering Mathematics ||
 ||'''Author'''|| Erwin Kreyszig ||
 ||'''Edition'''|| 8th Edition ||

/* code_begins */

{{{
A = matrix([[1, -1, 1], [-1, 1, -1], [0, 10, 25], [20, 10, 0]])
b = vector([0, 0, 90, 80])
x = A.solve_right(b)
print x

}}}

/* code_ends */

 * '''Solution by''': 
   * vasanthi, student, IIIT-Hyderabad