设李伟X岁,他爷爷Y岁.
得方程X+Y=110 ①,Y/X=4②,由①得110-X=Y,代入②得(110-X)/X=4得110/X=5,得X=110/5,X=22,再代入②得Y=88.
所以李伟22岁,他爷爷88岁