Two friends Moinul and Nuru have 40% and 60% share in a business. After some time a third friend Azmal joined the business by investing Tk 500,000 and acquired 20% shares in the business. What is the amount (in Tk) of Moinul in the business now?

Explanation: Azmal's shares = \(20\% = Tk.~500,000\). Total shares of Moinul and Nuru = \(100\% - 20\% = 80\%\). Moinul's original share was \(40\%\) of the original total, which is his share of the remaining \(80\%\) after Azmal joined. The ratio of Moinul to Nuru remains 40:60 (or 2:3) within the remaining 80%. Moinul's new share = \(40\% \times 80\% = 32\%\). If \(20\% = Tk.~500,000\), then \(32\% = (32/20) \times 500,000 = 1.6 \times 500,000 = Tk.~800,000\). The total value of the business is \(500,000 / 0.20 = Tk.~2,500,000\). Moinul's share is \(0.32 \times 2,500,000 = Tk.~800,000\).