Ratio and Proportion question bank (Quantitative Aptitude)

$P$ and $Q$ enter into a partnership. $P$ invests $Rs. 50$ and $Q$ invests $Rs. 45$. At the end of $4$ months,$P$ withdraws half of his capital,and at the end of the $5^{\text{th}}$ month,$Q$ withdraws half of his capital. $S$ then enters the partnership with a capital of $Rs. 70$. At the end of $12$ months,they earn a total profit of $Rs. 1272.5$. What was $S$'s share in the profit?

Aditya and Manish continued in a joint business for $36$ months. Aditya contributed $Rs. 300$ for a certain time and Manish invested $Rs. 500$ for the remaining time. If out of a total profit of $Rs. 1020$,Aditya gets $Rs. 495$,then for how long (in months) did Aditya keep his money?