3又3/5X(0.25+1又1/15)/2.4

问题描述:

3又3/5X(0.25+1又1/15)/2.4

3又3/5*(0.25+1又1/15)/2.4
=18/5*[5(1/4 + 16/15)]/12
=[3(1/4 + 16/15)]/2
=[3(15/60 + 64/60)]/2
=15/10 + 64/10
=7.9