I am having trouble with the following problem:
Fry travels in a rocket ship towards Leela, at constant relative speed $v$: Fry is delivering a pizza, which in its rest frame stays hot for exactly another 2 minutes. If Leela measures that Fry is 27 million kilometers away, then calculate the minimal value of $v$ for which the pizza is hot when delivered.
My approach was to use speed=distance/time and account for time dilation but I cannot figure out how to eliminate the Lorentz Factor. The answer is meant to be $3c/5$. Any pointers would be appreciated! Thanks.