-1/30÷（2/3-1/10+1/6-2/5）=?
问题描述：
-1/30÷（2/3-1/10+1/6-2/5）=?
答
=(-1/30)/[(2/3+1/6)-(1/10+2/5)]
=(-1/30)/[(4/6+1/6)-(1/10+4/10)]
=(-1/30)/(5/6-5/10]
=(-1/30)/(5/6-3/6)
=(-1/30)/(2/6
=-3/10