A man retired from his service at the age of $60$. He served for $\frac{3}{5}\mathrm{th}$ years of his retirement age. He joined his job at the age of:

A man purchased $120$ reams of paper at $₹80$ per ream. He spent $₹280$ on transportation, paid octroi at the rate of $40$ paise per ream and paid $₹72$ to a porter. In order to gain $8\%$, he must sell each ream of paper for: