reaction set: (find : needed for material balances ?)
  reactants   -> products
(peter.vlasschaert@gmail.com , 11/08/2016)
1e) '1'CH  + '1'CO  -> '2' CO + '2'H
         4        2                 2
2e) '1'CO +'1'H O  -> '1'CO  + '1' H 
               2           2        2
3e) '1'CH + '1'H O  -> '1'CO + '3' H
         4      2                   2
4e) '1'CH + '2'H O  -> '1'CO  + '4' H 
         4      2           2        2

fill in : Matrix ,row   : reactions 1e),2e),3e),4e)

                           1  2  3  4   5
                         ------------------
                  column: CH ,CO ,CO,H ,H 0
                            4   2     2  2  
number rows    : 4
number columns : 5
reactant : - 'value' , product : + 'value'

rec:matrix([-1,-1,2,2,0],[0,1,-1,+1,-1],[-1,0,1,3,-1],[-1,1,0,4,-2]);

 construct echelon matrix from 'rec'

echelon(rec);

result : reaction needed for 'material balances'

        we see above matrix 'echelon(rec)',build in 'Maxima'

     r1: '2'H  + '2' CO -> '1'CH + '1'CO
             2                  4       2
     r2: '1'CO + '1'H O -> '1'CO  + '1'H
                     2          2       2