Răspuns :
Numitor comun 60
(2x20+3x15+4x12+5x10)/60=
(40+45+48+50)/60=
183/60
(2x20+3x15+4x12+5x10)/60=
(40+45+48+50)/60=
183/60
2/3 + 3/4 = 8/12 + 9/12 = 17/12
4/5 + 5/6 = 24/30 + 25/30 = 49/30
17/12 + 49/30 = 85/60 + 98/60 = 183/60
Succes!