Răspuns :
x-pret initial
x+20%x=120%x
120%x-30%*120%x=120/100x-30*120/10000x=120/100x-36/100x=(120-36)/100x=84%x
84%x=420
x=420*100/84=500 lei
x+20%x=120%x
120%x-30%*120%x=120/100x-30*120/10000x=120/100x-36/100x=(120-36)/100x=84%x
84%x=420
x=420*100/84=500 lei