Răspuns :
a-234=234+321
a-234=555
a=555+234
a=789
VERIFICARE
789-234=555
SUCCES
a-234=555
a=555+234
a=789
VERIFICARE
789-234=555
SUCCES
des-descazut dif-diferenta
des-234=dif
dif=321+234=555 => des=555+234=789
des-234=dif
dif=321+234=555 => des=555+234=789