gia dinh lan co 4 nguoi ma chi co bo va me di lam . luong cua me moi thang la 275000 dong . luong cua ba gap doi luong cua me . moi thang me de danh 75000 dong . hoi :
a, moi thang trung binh moi nguoi da tieu bao nhieu tien ?
b, neu lan co them 1 nguoi em nua ma me van de danh nhu truoc thi so tien tieu trung binh hang thang cua 1 nguoi se giam bao nhieu ?