A certain number of persons can complete a work in 34 days working 9 h a day. If the number of persons is decreased by 40%. Then how many hours a day should the remaining persons work to complete the work in 51 days?

Solution (By Examveda Team)

\[40\% \to \frac{{ - 2}}{5}\begin{array}{*{20}{c}} {} \\ { \to \,{\text{Men}}} \end{array}\]
$$\eqalign{ & 9 \times 34 \times 5 = 3 \times 51 \times x \cr & x = 10{\text{ hours}} \cr} $$