Significance of 75% when calculating the offer amount?

[Juan Castro]

I've read a few articles where they talk about figuring out the maximum offer amount (ARV * 75% - Repair Cost = Offer Amount) but they don't go into detail as to the relevance of 75%. What does this percentage represent? Also, is this where you cover other costs (holding, closing, etc)? Lastly, how does this percentage change depending on strategy (Buy & Hold through BRRRR vs Flipping)?