Question

A fort has provisions for 300 men for 90 days.After 20 days, 50 men left the the fort then how long would the provisions last at the same rate?

Answer 1

here
300 men had provisions for 90 days.
after 20 days,
300 men had provisions for (90-20)=70 days. then present no of men =(300-50)=250 men
so, let the required no of days be x.
then,
no. of men - 300 250
no. of days -70. x
then, since if the no of men decrease then no of days increase.
so, they are inversely proportional.
then,
300/70=250/x
$300 \times 70 = 250x$
then
$x = 300 \times 70 \div 250$
then x= 84 days