ANSWER
It will take 35 people 3 hours.
EXPLANATION
A team of 15 workers can do a job in 7 hours.
Working at the same time rate, a team of 35 workers can do a job in less than 7 hours.
If less more divides.
This implies that, 35 people will take
[tex] = \frac{15 \times 7}{35} [/tex]
[tex] = 3[/tex]
Hence 35 people will finish in 3 hours.
