1)

A contractor undertook to do a certain piece of work in 9 days. He employed certain number of men, but 6 of them being absent from the very first day, the rest could finish the work in 15 days. The number of men originally employed were :

A) 12

B) 18

C) 15

D) 23

Let there be $x$ men at the beginning.
$15:9::x:(x-6)$ $\Leftrightarrow 15(x-6)=9x$
$\Leftrightarrow 6x=90$ $\Leftrightarrow x=15$