1. 20/12 = 25/x => 12 x 25 / 20 = 30
2. 12/30=x/45 => 12 x 45 / 30 = 18
3. 15/8 = 37,5/x => 8 x 37,5 / 15 = 20
4. 7/35 = 10/x => 35x10/7 = 50 ( in 10 ore)
7/35=12/x => 35 x 12/7 = 60 ( in 12 ore)
7/35=20/x => 35x20/7 = 100 ( in 20 de ore )
Sper ca ai inteles , ca sa stii asta : / este linia de fractie ;)