x-suma depusa la banca
I an: x+15x/100=(100x+15x)/100=115x/100=simplif cu 5=23x/20
II an: 23x/20+15/100·(23x/20)=simplif=23x/20+3/100·23x/4=
=23x/100+69x/400=(20·23x+69x)/400=529x/400
529x/400=13225/100
529x·100=13225·400
x=5290000/52900
x=100 lei s-a de pus la banca
verificare
I an: 100+100·15%=100+15=115 lei
II an: 115+115·15%=115+17,25=132,25 lei