Let initially the number of passengers was x
Number of passengers after first halt = \( \Large \frac{x}{2}+125 \)
Number of passengers after second halt = \( \Large \frac{1}{2} \left(\frac{x}{2}+125\right) \)
By hypothesis,
\( \Large \frac{1}{2} \left(\frac{x}{2}+125\right)+100 = 250 \)
= \( \Large \frac{1}{2} \left(\frac{x}{2}+125\right)=150 \)
=> \( \Large \frac{x}{2}+125 = 300 \)
=> \( \Large \frac{x}{2} = 175 \)
=> x = 350