31又2/7-22又6/13+4又5/7+11又6/13
=31+2/7-22-6/13+4+5/7+11+6/13
=31+4+11-22+2/7+5/7+6/13-6/13
=24+1
=25
3^2003-5*3^2002+6*3^2001
=3^2*3^2001-5*3*3^2001+6*3^2001
=9*3^2001-15*3^2001+6*3^2001
=(9-15+6)*3^2001
=0*3^2001
=0
（-5.5）+（-3.2）-（-2.5）-4.8
=-5.5-3.2+2.5-4.8
=2.5-5.5-3.2-4.8
=-3-(3.2+4.8)
=-3-8
=-11