3 men or 5 women can do a work in 12 days. How long will 6 men and 5 women take tc!.'; do It?

(a) 6 days

(b) 5 days

(c) 4 days

(d) 3 days

3 men =5 women

1 man $=\frac{5}{3}$ women

6 men $=\frac{5}{3}\times 6=10$ women

$\therefore$ Total women in second case.

=10+5=15 women

Now,

5 women :15 women:: 12 days:x

$\therefore$ By inverse proportion

5 : 15 :: x : 12

$x=\frac{5\times 12}{15}=4$ days