Number of females = f
Total number of people in audience = n
0.4n = f
f + (f+ 100) = n
2f + 100 = n
Find n:
f = 0.4n --> Replace f with 0.4n in the equation 2f +100 = n
2(0.4n) + 100 = n --> Multiply out the brackets
0.8n + 100 = n --> Subtract 0.8n from both sides
100 = 0.2n --> To get n, multiply both sides by 5
n = 500
There were 500 people in the audience.
Let's evaluate the ratio test:
The limit as 
of this quantity is 3, which is more than 1. So, the series diverges.
Answer and work down below
