Question 205499
In x amount of time Dennis travels 60km (typo in question?) and in that same amount of time Elena travels 84km

You set up a porportion like so {{{84/60}}} when simplified out the ratio of Elena's distance traveled to Dennis' is 1.4

Because speed and distance are directly related (remember {{{S=(D/T)}}})
the ratio between Elena's speed and Dennis' speed is also 1.4

Elena is going 1 and {{{2/5}}} the speed of Dennis because .4 = {{{2/5}}}
if {{{2/5}}} of Dennis' speed is 8 km/h then 
{{{8*(5/2) = 20}}} multiply by the reciprocal

so Dennis is Going 20 km/h and Elena is going 28 km/h