小明早上7:45出发去南北湖,下午4:15回到家,他在南北湖共游览8.5小时. .
=3÷2=15: = %= (小数)
0.6=3: = ÷15= 成= %
4: == ÷10= %
36÷ ==0.4=4: = %
:20==80%=20÷ = (填小数)