You have the right answer. n + p = m because inside angle + inside angle = outside angle.
First, 4 people know the post
Then, those 4 people share it each with 4 people (4 * 4 = 16)
Then, each of those people share it with another 4 people (16 * 4 = 64)
And so on. the function is as simple as: 4^x (4 to the power of x)
0.9x = 450
x = 450/0.9
x = 500
Answer = 500
