Verified answer

а) АВ+MN+BC+CA+PQ+NM = (АВ+BC+CA)+(NM +MN)+PQ = PQ;

b) FK+MQ+KP+AM+QK+PF = (FK+KP+PF)+(AM+MQ+QK) = AK;

в) KM+DF+AC+FK+CD+CA+MP = (CD+DF+FK+KM+MP)+(AC+CA) = CP;

г) AB+BA+CD+MN+DC+NM = (AB+BA)+(CD+DC)+(NM+MN) = 0