1.(1/2-1)(1/3-1)(1/4-1)(1/5-1)(1/6-1)
=-(1/2)*(2/3)*(3/4)*(4/5)*(5/6)
=-1/6;
2.(-2)+(-5)-(-3)
=-2-5+3
=-4;
3.-0.65+(-1.9)-(+1.1)-(-13/20)
= -0.65-1.9-1.1+0.65
=-3;
4.15x+4y-10y-7x
=(15-7)x+(4-10)y
=8x-6y;
5.2(3a+b)-(3a-b)-3(a-2b)
=6a+2b-3a+b-3a+6b
=(6-3-3)a+(2+1+6)b
=9b;
6.-5+6÷(-2)×1/3
=-5-3*(1/3)
=-5-1
=-6.