A := matrix(4,5,[100,10,1,-1,0,15,15,15,-1,0,1,10,100,-1,396,-1,-1,1,0,1]):
A1 := swaprow(A,1,4):
A2 := mulrow(A1,1,-1):
A3 := addrow(A2,1,2,-15):
A4 := addrow(A3,1,3,-1):
A5 := addrow(A4,1,4,-100):
A6 := swaprow(A5,2,3):
A7 := mulrow(A6,2,1/9):
A8 := addrow(A7,2,4,90):
A9 := mulrow(A8,3,1/30):
A10 := addrow(A9,3,4,-1111):
A11 := mulrow(A10,4,30/781):