(2/3)+(11/4)÷(11/15)×(1/5)+(1/4)
=(2/3)+(11/4)×(15/11)×(1/5)+(1/4) 除以一个数等于乘以这个数的倒数
=(2/3)+(3/4)+(1/4)后面两项为同分母
=(2/3)+1
=5/3