18 men or 25 boys can complete a work in 25 days. How many days will 36 men and 10 boys will take to complete the work?

Let time taken by 1 man to complete unit work = $$m$$ and by 1 boy = $$bb$$

18 men complete the work in 25 days, => $$m=\frac{1}{25\times18}$$

Similarly, $$b=\frac{1}{25\times25}$$

Now, time taken by 36 men and 10 boys to complete unit work = $$36m+10b$$

= $$(36\times\frac{1}{25\times18})+(10\times\frac{1}{25\times25})$$

= $$\frac{2}{25}+\frac{2}{125}$$

= $$\frac{10+2}{125}=\frac{12}{125}$$

$$\therefore$$ No. of days taken to finish the work = $$\frac{125}{12}$$

=> Ans - (B)