Answer & ExplanationOption: [C]
On the second day he spend Rs. 250. i.e. he earns Rs. 70
On the third day he again earn Rs. 320 and spend Rs. 70. Thus he save Rs. 70 again.
Thus it is seen that he save Rs. 70 in every 2 days.
So, he earn Rs. 1050 in 1050/70 x 2 = 30 days.