1) 2/15+3/20+4/35= Aflam n.c. care este c.m.m.m.c al numitorilor
15=3×5; 20=2²×5; 35=5×7
c.m.m.m.c=2²×3×5×7=420
Aducem fractiile la acelasi numitor ⇒
56/420+63/420+48/420=167/420
2) 3/11+2/5+1/2= numitorul comun=110 ⇒
30/110+44/110+55/110=129/110
3) 7/20+1/30+7/60= n.c.=60
21/60+2/60+7/60=30/60=1/2
7,575=7575/1000=303/40
5,(72)=(572-5)/99=567/99=63/11
4,8(3)=(483-48)/90=435/90=145/30=29/6
