①3/4*2/7+5/7÷3/4 ②68/69*69

问题描述:

①3/4*2/7+5/7÷3/4 ②68/69*69

①3/4*2/7+5/7÷3/4
=3/4*2/7+5/7*4/3
=3/4*2/7+2/7*10/3
=(3/4+10/3)*2/7
= 49/12*2/7
=7/6
②68/69*69
=68*69/69
=68