Let man's salary be Rs. NMoney spend on food =N/7Money spends on clothing = (N - N/7) x 1/2 = (6N/7) x (1/2) =3N/7Money spend on entertainment = (N - N/7 - 3N/7)/3 = (7N - 4N)/7 = N/7Now, 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
Let the length of lamppost = L mThen,first part = L/3and second part = (3/8) x L/3 = L/8 and third part = 6 m 50 cm = 6.50 mFirst part + second part + Third part = length of lamppost ⇒ L/3 + L/8 + 6.5 = L ⇒ L - L/3 - L/8 =6.5 ⇒ (24L - 8L - 3L)/24 = 6.5 ⇒ 13L/24 = 6.5 ∴ L = (65.x 24)/13 = 12 m