A person on tour has Rs. 4200 for his expenses. If he extends his tour for three days; he has to cut down his daily expenses by Rs 70. Find the original duration of the tour.
Let the original duration of the tour be x days
Daily expenses 
tour extended for 3 more days
Hence total number of days = x + 3
Daily expenses 
According to the question,
4200(x + 4)–4200x = 70x(x + 3)
4200x + 16800–4200x = 70x2 + 210x
70x2 + 210x–16800 = 0
We divide bye 7 in both the side
X2 + 3x – 240 = 0
(x + 15)(x–12) = 0
x = –15, 12
So the total duration is 12 days
80