HSC - পদার্থ বিজ্ঞান ২য় পত্র→অধ্যায়-০১ঃ তাপগতিবিদ্যা→তাপ ইঞ্জিন

A Carnot engine whose sink is at $300\ K$ has an efficiency of $40\%$. By how much should the temperature of source be increased, so as to increase its efficiency by $50\%$ of original efficiency?