Answer:
1. 15+5i
2. 3+4i
3. 3+i
4. 30
Step-by-step explanation:
Combinations
nCr
you have n items and how many ways are there to chose r of them
nCr=

remember than n! means n times all numbers before like
3!=3*2*1, 5!=5*4*3*2*1
9 stations, how many ways are there to chose 6 of them
9C6=

=

=

=

=

=
84
84 ways
Answer:
517 minutes
Step-by-step explanation:
60 minutes per hour.
8 x 60 = 480
37 minutes, 480 + 37 = 517