Question

A garrison of 1200 men has provisions for 15 days. How long will the provisions last if the garrison be increased by 600 men?

Answer 1

No. of days 1200 men has provisions = 15 days
No. of days 1 man has provisions = 15 $\times$ 1200 days
No. of days 1200 + 600 = 1800 men has provisions = (15 $\times$ 1200)/ 1800 = 10 days