Let's talk CHILD SUPPORT

So, I just saw a post where parents were arguing over child support. The father was paying 300 a month and the mother demanded another 200 because she'd spent the initial 300, on bills. I saw a lot of women saying that 300 is not a lot of money for a [child].

So my question is: What is a reasonable amount of money for a parent to pay for child support, per month? And also, what should child support cover?