In a camp of persons there was a provision of food for 42 days. After 10 days the number of persons increased by 300 as a result of which the food lasted only 24 days. What was the number of persons in the camp, originally ?

The correct answer is (b).

Let $x$ be the number of persons in the camp originally. After 10 days, the number of persons is $x+300$. The food lasts for 24 days, so the total amount of food is $24(x+300)$. The food was originally enough for 42 days, so the total amount of food is $42x$. We have the equation $24(x+300)=42x$. Solving for $x$, we get $x=375$.

Option (a) is incorrect because 100 people would have food for 42 days, but after 10 days, there