Ansen 和 Beirul 喝光了一瓶水。Ansen 喝的水比整瓶水总量的 $\frac{3}{8}$ 还多 100 ml。Beirul 喝了 250 ml。这瓶水最初有多少水？

1. Determine the fraction of water that corresponds to the remaining amount after taking away 3/8 of the total.

Total water $= 1 = \frac{8}{8}$
Remaining fraction $= 1 - \frac{3}{8} = \frac{5}{8}$

2. Equate the remaining fraction to the actual volume of water left.

The remaining $\frac{5}{8}$ of the water is made up of the extra $100$ ml Ansen drank and the $250$ ml Beirul drank.
$\frac{5}{8}$ of total $= 100 + 250 = 350$ ml

3. Find the total amount of water in the bottle.

$5$ units $= 350$ ml
$1$ unit $= 350 \div 5 = 70$ ml
Total ($8$ units) $= 70 \times 8 = 560$ ml