1. Regula de 3 simpla 145 .........100%
x ..........120% x = 145*120/100 = 174
2. La fel: 10 ............100
x ........... 10 x = 10*10/100 = 1 nerez 9 rezolvate.
3. 12% .................3.6
100% ................ x x = 100*3.6/12 = 30
4. 0.5 .................15
100 .................. x x= 100*15/0.5 = 3000