(-1/30)/(2/3-1/10+1/6-2/5)的倒数为:(2/3-1/10+1/6-2/5)/(-1/30)
则:(2/3-1/10+1/6-2/5)/(-1/30)
=(2/3-1/10+1/6-2/5)×(-30)
=-30×2/3+30×1/10-30×1/6+30×2/5
= -20+3-5+12
= -10
则(-1/30)/(2/3-1/10+1/6-2/5)= -1/10
解:
原式的倒数为:
( 2/3一 1/10+ 1/6- 2/5)÷(- 1/30)
=( 2/3一 1/10+ 1/6- 2/5)×(-30)
=- 20+3-5+12
=-10
故原式=- 1/10