Question 755170
Try a more general approach just to understand.

q revolutions at p revolutionsPerMinute.


if p is a rate, revolutions per minute, and x is a time, minutes, then you may have {{{p*x=q}}} and you treat this as any other "uniform rates" problem.


Now you want to solve for x which is the amount of minutes.  You have the rate and you have the amount; you have p and you have q; but you want to find x.


{{{x=q/p}}}
{{{x=140/(39&2/3)}}}  ________about 3.53 minutes.


... or {{{3*140/119}}}