I could use some help with my normal distripution assigment

[NikkeA]

A and B have decided to meet at the train station. They leave at the same time by bus from A and B. Assume that the bus times are independent and follow the distributions of A: N(30, 8^2 ) B: N(20, 6^2)

a) What is the probability that A arrives first?

b) What is the probability that the first one who arrives will not have to wait other any longer than 10 minutes?

I have no idea what do.

 

[Prof]

What does the notation N(30,8^2) mean. I assume 30 is the mean, but what does the 8^2 mean?