如果向东走2km记作+2km,那么﹣8km的意义是 ,向西走6km记作 .
=9÷ = :8== (填小数)
3: ==15÷ = ×= (小数).
5÷20==4: = :12= %= (填小数)
÷20=12: ==0.8= %.
= : =15÷ ==0.6.