A camp of 150 soldiers has food for 400 days. After 50 days, 100 more soldiers join the camp. For how many days will the food last from then onwards?

210 days

Formula to be used here,

\( { M}_{1 } \) x \( { D}_{1 } \)  = \( { M}_{2 } \) x \( { D}_{2 } \)

where M = No. of men, D = No. of days,

⇒ Putting values in the formula,

⇒ 150 x 350 = 250 x \( { D}_{2 } \)

⇒ \( { D}_{2 } \) = 210 days.