so we have 11400 +11400×x=12711 this represents the original price plus some percentage of the original price is equal to the new price. now all we need to do is solve for x so 11400+11400x=12711 subtract 11400 from each side 11400x=1311 now divide both sides by 11400 x=.115 or about 12% we can. check by finding 12% of the original price. 11400×.12=1368 now add to 11400 11400+1368=12768 so we are a bit over. this is because it is actually 11.5% just depends on how accurate your answer needs to be