I'm playing an idle game. One thing it does is it auto-regenerates mana over time. I have a booster that increases the mana regen rate over time, determined by how many seconds I've been playing the game.

The rate is: floor(2.5 * x0.5) / 10

Where x is the number of seconds I've been playing this game.

The base mana regen rate I have is 180 mana per second.

How much time would it take to reach 300 mana per second?