4 boys = 3 men
\therefore 1 boys =\large\frac{3}{4} men
\therefore 8 boys =\large\frac{3\times8}{4} men
\rightarrow 6 men.
So, 7 men and 8 boys =\left(7+6\right) men
\rightarrow 13 men.

Here,
Men and Hours are inversely proportional to Days.
and, Work and Days are Directly proportional.
\therefore x=65\times\large\frac{3}{13}\normalsize\times\large\frac{8}{10}\normalsize\times\large\frac{5}{1}
\rightarrow x=60 Days
Ans: 7 men and 8 boys, each working for 10 hours per day, will complete 5 times the previous amount of work in 60 days.