6 songs
The way to find this answer is to divide 18 by 3, which is six, which means that after every six songs a commercial is played.
Hope this was helpful and that I explained it correctly.
B is plus square so you would add
5,309 divided by 43 is equal to 123.4651162790698
I'm assuming you want to find the wind speed.
the ground speed against the wind is 410.
2460 / 6 = 410
the ground speed against the wind is 492.
2460 / 5 = 592
the difference is 82 mph, but you need to divide by 2 because speed is being added in one direction and subtracted in the other.
82 / 2 = 41
your final answer is 41 mph.