Question

An army of 2000 men had enough food to last for 30 days. After 10 days 500 moremen joined them. How long did the food last then ?

Answer 1

total no of units of food = 2000*30=60000 units of food
no. of units consumed in 10 days = 2000*10=20000 units
no of units left = 60000 - 20000 = 40000 units
after arrival of 500 soldiers, no of soldiers = 2500
no of days= units of food / no of soldiers
               = 40000 / 2500
               = 16 days