全长=360÷(1-1/4-40%)=7200/7米 怎么得的 =7200/7米怎么算?

问题描述:

全长=360÷(1-1/4-40%)=7200/7米 怎么得的 =7200/7米
怎么算?

=360÷(3/4-2/5)
=360-7/20
=360×20/7
=7200/7

360÷(1-1/4-40%)
=360÷0.35
=360×20/7
=7200/7