走同一段路,甲要4时,乙要3时.在这段路上,甲和乙的速度比是 .
× = ÷== %.
27÷ == :2== (填小数)
== ÷12= (小数)
=9: = :20= ÷ a:4=3a: = :4+2.
=4÷ = (填小数)= %