Normal Distrubution A level

Hi, I've been trying to do this Statistics question, I'm a bit confused about part c?

The number of miles Mark’s motorbike can travel on a full tank of petrol, can be modelled by a Normal distribution with a mean of 135 and a standard deviation of 12.
a) Determine the probability that Mark can travel at least 165 miles on a full tank of petrol.
I got 0.0061
b) Find, to the nearest mile, the longest journey that Mark can make, if he is to have at least a 90% chance of completing it on a single full tank of petrol.
120

c) Given that Mark has a 90% chance of completing a journey on a single full tank of petrol find the probability that this journey will not exceed 165 miles?

I know its conditional probability but which values would you use? Thank you so much

What is the conditional formula and what do the A and B represent here?