x-pretul initial
20% din x= 20/100*x= 2/10 *x= 1/5 *x= x/5-ieftinirea
x-x/5= (5x-x)/5= 4x/5-restul
20% din 4x/5= 20/100* 4x/5= 2/10*4x/5= 1/5 *4x/5= 4x/25 -majorarea
4x/5 +4x/25= (20x+4x)/25= 24x/25 -noul pret
24x/25=288
x=25*288/24
x=25*12
x=300 lei