Find the next number in the series:
$280,275,265,245,\dots$

Let's find the difference between consecutive numbers:
$$275-280=-5$$

$$265-275=-10$$

$$245-265=-20$$

The difference values are doubling each step: $-5,-10,-20$.
Following this pattern, the next difference should be $2\times (-20)=-40$.

Therefore, the next number is:

$$245-40=205$$