Răspuns :
a+190+190:10=300
a+190+19=300
a+190=300-19
a+190=281
a=281-190
a=91
Verificare:
91+190+190:10=300
281+19=300
300=300
a+190+19=300
a+190=300-19
a+190=281
a=281-190
a=91
Verificare:
91+190+190:10=300
281+19=300
300=300