1. -21+14÷(-7)=-21-14÷7=-21-2=-23
2. 17-8÷(-2)+4*(-5)=17+8÷2-4*5=17+4-20=1
3. (-4)*(-3)-5*(-7)-2*2*2*2=12+35-16=31
4. -5/3*(0.5-2/3)÷(-7/6)=-5/3*(3/6-4/6)÷(-7/6)=-5/3*(-1/6)÷(-7/6)=-5/18÷7/6=-5/18*6/7=-5/21
5. -3/2*[-9*(-8/27)-2]=-3/2*[8/3-2]=-3/2*2/3=-1