100+2x50+20+3x10+4=254 lei
254 lei _________ 100%
a _____________ 12%
a=(254x12)/100=3048/100=30,48 lei i-au ramas Alisiei
=> A cheltuit 254-30,48=223,52 lei
254 lei __________ 100%
b _______________ 20%
b=(254x20)/100=5080/100=50,80 lei
=> Ar trebui sa cheltuie 254-50,80=203,2 lei