How long will the supplies then last?

Twelve people purchased supplies for a ten-day camping trip with the understanding that each of the twelve will get equal daily shares. They are then joined by three more people, but make no further purchases. How long will the supplies then last if the original daily share for each person is not changed?

MetroEye: Rate of Work

Here \(M_1\) = 12
\(H_1\) = 10 days
Let supplies = S

When 3 more people joined, \(M_2\) = 12+3 = 15

As per the MetroEye, \(\dfrac{S}{12\cdot 10}\) = \(\dfrac{S}{15\cdot H_2}\)
=\(\dfrac{120}{15}\) = 8

The original supplies will last only for 8 days.