In an army camp, 300 soldiers had provisions for 13 days. If 40 of them are transferred to the other camp, how long will the provisions last?

Original soldiers = 300.

Remaining soldiers = 300 - 40 = 260.

Provisions for 300 soldiers last = 13 days.

Provisions for 1 soldier last = (13 x 300) days. $\quad$ [Less soldiers, More days]

Provisions for 260 soldiers last = $\Big(\dfrac{13 \times 300}{260}\Big) \text{ days} \quad \text{[More soldiers, Less days]}$

= $\Big(\dfrac{1 \times 300}{20}\Big) \text{ days} \quad \text{[Dividing 13 and 260 by 13]}$

= 15 days.

260 soldiers had provisions for 15 days