x-pretul initial al pantofilor
dupa majorare: x+15x/100=(100x+15x)/100=115x/100
dupa micsorare: 115x/100-15/100·(115x/100)=115x/100-1725x/10000=
=(11500x-1725x)/10000=9775x/10000
9775x/10000=1955/10
10·9775x=1955·10000
97750x=19550000
x=19550000/97750=1955000/9775=200
x=200 lei pretul initial al pantofilor
b) pretul dupa majorare
200+200x15/100=200+30=230 lei