dobanda incasata : 100 000 x 40% = 40 000 u.m.
dobanda platita : 130 000 x 30% = 39 000 u.m.
castig bancar : 40 000 - 39 000 = 1 000 u.m.
cheltuieli administrative : 1 000 x 70% = 700 u.m.
castig bancar - cheltuieli administrative = profit
1 000 - 700 = 300 u.m.