A lady went shopping and bought one red bag and 15 black bags. The cost of the red bag was 3 times the average cost of a black bag. If she had spent a total of Taka x for the bags, what was the cost of the red bag (in terms of x)
Explanation: মনে করি, average এ প্রতিটি black bag এর দাম 'b' taka. অতএব, প্রতিটি red bag এর দাম '3b' taka. According to the question, \(3b+15b=x \Rightarrow b=x/18\). \(\therefore 3b=x/6\).
