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
Given Expression = (.53)³ - (.42)³- 3 x .58 x .42 x (.58-.42)= a³-b³ -3ab(a - b) = (a - b)³(where a = .58 and b=.42)= (.58 - .42 )³ = .16 x .16 x .16 = 0.004096