-0.3+3又4分之1+2.6-5又2分之1+1.15
=-0.3+3.25+2.6-5.5+1.15
=（3.25+1.15+2.6）-(0.3+5.5)
=7-5.8
=1.2
如果本题有什么不明白可以追问,