a) एउटा क्याल्कुलेटरको क्रय मूल्य यसको विक्रय मूल्यको 5 भागको 4 भाग छ । यसमा नाफा प्रतिशत पत्ता लगाऊ।
The cost price of a calculator is four-fifth of its selling price. Find the percentage of gain on it.
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