1/5+1/2+4/5 =1/5+4/5+1/2 =1+1/2 =1/1/2 18/11+(3/11-1/16) =18/11+3/11-1/16 =1-1/16 =15/16 5/9+7/12+4/9 =5/9+4/9+7/12 =1+7/12 =1/7/12