4/7+2/7 =(4+2)/7 =6/7 4/5-3/5 =(4-3)/5 =1/5 1/6+1/10 =5/30+3/30 =(5+3)/30 =4/15 12*(5/9)+1/6 =20/3+1/6 =40/6+1/6 =41/6
