18/7*5/4+11/18/4/5=18/7*5/4+11/18*5/4=(7/18+11/18)x5/4=1x5/4=5/4
7/18*5/4+11/18/4/5=7/18*5/4+11/18*5/4=5/4(7/18+11/18)=5/4