A work can be completed by X men in 15 days. 10 more men join them after 3 days. The remaining work is now completed in 8 days. What is the value of X?

20

Formula to be used here,

\( { M}_{1 } \) x \( { D}_{1 } \)  = \( { M}_{2 } \) x \( { D}_{2 } \)

where, M = No. of Men, D = No. of Days,

⇒ Putting the values in the formula,

⇒ X x 15 = (X x 3) + (X + 10) x 8

⇒ 15X = 3X + 8X + 80

⇒ 15X - 11X = 80

⇒ 4X = 80,

⇒ X = 20.