[tex]v=\frac{s}{t}\\\\v=30\ mph\\\\s=20\ mi\\\\subtitute\\\\30=\frac{20}{t}\to\frac{30}{1}=\frac{20}{t}\ \ \ |cross\ multiply\\\\(30)(t)=(1)(20)\\\\30t=20\ \ \ \ |divide\ both\ sides\ by\ 30\\\\t=\frac{20}{30}\to \huge\boxed{t=\frac{2}{3}\ (h)}[/tex]
[tex]1\ h=60\ min\\\\therefore\\\\\frac{2}{3}\ h=\frac{2}{3}\cdot60\ min=2\cdot20\ min=\huge\boxed{40\ min}[/tex]
