gistfile1.txt

(%i1) eq1: a = b + c / d;
                                       c
(%o1)                              a = - + b
                                       d
(%i2) eq2: x = b - c*d;
(%o2)                             x = b - c d
(%i3) solve([eq1, eq2], [a,b,c,d, x]);
(%o3) [[a = %r1, b = %r2, c = (%r1 - %r2) %r3, d = %r3, 
                                                                      2
                                                   x = (%r2 - %r1) %r3  + %r2]]