Let the unit of work done by 1 man in 1 hour and 1 day be 1MDH unit (Man Day Hour). Thus, in 7 hours per day for 10 days, the work done by N people =N×7×10MDH units. Since this is equal to 35% of the total work, 35% of the total work =N×7×10MDH units. Total work =
(N×100×7×10)
35
=200×N MDH units. The work left =200N−70N=130N MDH units. Now, 10 people left the job. So, the number of people left =(N−10) Since (N−10) people completed the rest of work in 14 days by working 10 hours a day, (N−10)×14×10=130N 10N=1400 N=140 Thus, the correct option is D.