% #6
A=[ 3 0 0 -1; 1 0 -2 0; 4 6 -8 -3; 0 1 -3 0; 0 2 0 -1]
rref(A)
% need to multiply answer by 6 to get integer values for the amount of the chemicals

%#12

B=[1 0 -1 -1 0 40; 1 1 0 0 0 200;0 1 1 0 -1 100; 0 0 0 1 1 60]
rrefB=rref(B)