a.I____I120I
b.I____I
c.I____I120I60I
Suma lor este 5940 deci facem suma partilor cunoscute :
120+120+60=300 (s.p.c.)
5.940-300=5.640 ( suma partilor egale)
5.640:3=1.880 (nr. b )
1880+120=2.000( nr. a)
1880+120+60=2.060 (nr. c )
Verificare : 1.880+2.000+2.060=5.940