keeping in mind that there 60 seconds in 1 minute, and about 1.609 kilometers in 1 mile.
[tex] \bf \cfrac{3.8~\underline{km}}{\underline{sec}}\cdot \cfrac{mi}{1.609~\underline{km}}\cdot \cfrac{60~\underline{sec}}{min}\implies \cfrac{3.8\cdot 60~mi}{1.609~min}~~\approx~~141.7029~\frac{mi}{min} [/tex]
