“marla starts running around a circular track at the same time nick starts walking around the same circular track. marla complets 32 laps around the track per hour and nick completes 12 laps around the track per hour. how many minutes after marla and nick begin moving will marla have completed 4 more laps around the track than nick?”

I solved this using relative speed, but someone did it slightly different than me and i want to know if what i did was correct or if i got lucky.

I found the relative speed to be (32/60)-(12/60) = (20/60) (laps per hour).

i then solved for the work 4

4=(1/3)t and got time = 12 minutes

someone else solved this by setting it to 4 = 20t and then (4/20)=t is 1/5 and 1/5 of an hour is 12 minutes.

thanks!