$P, Q$ and $R$ can finish a work in $10, 12$ and $15$ days respectively. If $Q$ stops after $2$ days,how long would it take $P$ and $R$ to finish the remaining work? (in days)

$A$ $10\, \text{hectare}$ field is reaped by $2\, \text{men},$ $3\, \text{women},$ and $4\, \text{children}$ together in $10\, \text{days}.$ If the working capabilities of a man, a woman, and a child are in the ratio $5: 4: 2,$ then a $16\, \text{hectare}$ field will be reaped by $6\, \text{men},$ $4\, \text{women},$ and $7\, \text{children}$ in how many days?

$10$ men can complete a piece of work in $15$ days and $15$ women can complete the same work in $12$ days. If all the $10$ men and $15$ women work together,in how many days will the work get completed?

$2$ men alone or $3$ women alone can complete a piece of work in $4$ days. In how many days can $1$ woman and $1$ man together complete the same piece of work?

$A$ can do $50\%$ of the job in $16$ days,$B$ can do $\frac{1}{4}^{th}$ of the job in $24$ days. In how many days can they do $\frac{3}{4}^{th}$ of the job working together?

$A$ can complete a piece of work in $40$ days. He starts working,but having some other engagements,he leaves after $5$ days. Thereafter,$B$ completes the remaining work in $21$ days. How many days would $A$ and $B$ take to complete this work working together?