x-cantitatea initiala
10% din x = 10/100 * x= 1/10 * x= x/10 -prima pierdere
x-x/10= (10x-x)/10= 9x/10 - restul
5% din 9x/10= 5/100 * 9x/10= 1/20 * 9x/10= 9x/200 -a doua pierdere
9x/10 - 9x/200= (180x-9x)/200 = 171x/200 - noul rest
171x/200= 171
x=200*171/171
x=200