If 45 men and 60 boys can do a piece of work in 20 days. How many days will 15 men and 20 boys take to complete the work?

Q. If $3$ men or $6$ boys can do a work in $20$ days, how many days will $6$ men and $8$ boys take to do the same work?

Q. If 2 men and 3 boys can do a piece of work in $3\frac{3}{7}$ days, while 3 men and 2 boys can do it in days, then in $3\frac{15}{43}$. Then in how many days will 4 boys finish the work?