a) Aflati un numar stiind ca inmultindu-l cu 2/5 obtinem 8/25

Răspuns :

x * 2/5 = 8/25

x = 8/25 : 2/5

x = 8/25 * 5/2

x = 4/5  
a x 2/5= 8/25
a=8/25 :2/5
a=8/25 x 5/2
a=4/5