<PRE><B>Question 921442</B>
if the food for 15 people lasts in 210 days
amt of food available as measured in people-days
15 * 210 = 3150
:
after 10 days 15 members are added then the food will last for how many days
let d = no. of days after 15 members are added, then a total of 30 members
15*(10) + 30d = 3150
150 + 30d = 3150
30d = 3150-150
30d = 3000
d = 3000/30
d = 100 days after 15 more were added </PRE>