设丁丁原来有X本,小胖有Y本。则X-5=Y+53(X-15)-2=Y+15联立得X=26.Y=16
设丁丁有X本,小胖有Y本。X-5=Y+5,(X-15)*3-2=Y+15
丁丁x 小胖yx-5=Y+5X-Y=103(X-15)-2=Y+153X-Y=62X=26Y=16