Urgent math question!

<p>I was doing test #5 in the blue book.
In section 2, problem 13 reads the following:
The total daily cost c, in dollars, of producing x units of a certain product is given by the function c(x) 5 (600x-200)/x 1k, where k is a constant and x#100. If 20 units were produced yesterday for a total cost of $640, what is the value of k?</p>

<p>The answer is 50.
I have no idea what x#100 means, or why there's no equals sign in the equation of the function, and why there's a "1" before the k. I've never before encountered this format of writing a function... Please help!</p>

<p>It's a typo.</p>

<p>Oh. Do you know what it was supposed to be?</p>

<p>GRRRR that bugs the crap out of me.</p>

<p>x=100 I think? Complete guess.</p>