Question

you are traveling down the interstate averaging 50 MPH. How much has passed when you have traveled 120 miles?

Answer 1

I assume you are asking how much time has passed
now, we can set up a proportion with this:
let x = time(in hours)
$\frac{120miles}{50miles} = \frac{x}{1 hour}$
we cross multiply to get:
$50x=120$
divide both sides by 50 to get:
$x= \frac{120}{50} =2.4= \frac{12}{5}=2 \frac{2}{5}$ hours