x-nr
16% din x= 16/100 *x= 8/50*x= 4x/25-marirea
x+4x/25= 25x+4x/25= 29x/25-noul nr
16 % din 29x/25= 16/100 *29x/25= 4/25 *29x/25= 116x/625-reducerea
29x/25-116x/625=725x-116x/625= 609x/625
x-16= 609x/625
625x-10 000=609x
625x-609x=10 000
16x=10 000
x=625