用简便方法计算46×7/45 2/3×5/4除以10/9 24×2/7×5/72×21 8/13除以7+1/7×6/13

46×7/45 =(45+1)*7/45=7+7/45=7又45分之72/3×5/4除以10/9 =10/12*9/10=3/424×2/7×5/72×21 =24*5/72*2/7*21=5/3*6/7=10/78/13除以7+1/7×6/13=8/13*1/7+1/7*6/13=2/13*7（4+3）=2/13