A passenger on an interplanetary express bus traveling at v=0.99c takes a five minute catnap, according to his

A passenger on an interplanetary express bus traveling at v=0.99c takes a five minute catnap, according to his watch.
A.How long does the nap last from your vantage point on a fixed planet?
B.If the bus slowed to 10% of the speed of light, how long would you measure the passenger’s catnap to be?

http://www.fourmilab.ch/cship/timedial.html

1/(1-[v^2/c^2])^-2 You do the math! As a check, I get (1.) a bit more than 4 hrs, and (2.) less than 30 mns .

This is hard !