(1),2又3/4+0.25-(-7又1/2)+(-2又1/4)-1.5-2.75(2),-12又1/3-[10又1/3+(-8又1/3)-3又2/3](3),如果|a|=3,|b|=1,求:(1)|a-b|的值 (2)若a>b,求a+b的值(4),计算:(+1)+(-2)+(+3)+(-4)+......+(+99)+(-100)(5),(-27)/9(6),-0.125/8/3(7),(-0.91)/(-0.13)(8),(-23)/(-3)*1/3