A man spends (1/7)th of his salary on food, half of the remaining on clothing and (1/3)rd of the remaining on entertainment. He is still left with Rs. 600. How much does he spend on entertainment?

Let man's salary be Rs. N
Money spend on food =N/7
Money spends on clothing = (N - N/7) x 1/2 = (6N/7) x (1/2) =3N/7
Money spend on entertainment = (N - N/7 - 3N/7)/3 = (7N - 4N)/7 = N/7
Now, money left =600
⇒ N - N/7 - 3N/7 - N/7 = 600
⇒ 7N - 5N/7 = 600
⇒ N = 600 x 7/2 = Rs. 2100
∴ Money spend on entertainment = 1/7 x 2100 = Rs. 300