$A$ man sold a cow at a loss of $12 \%$. If he had sold it at a gain of $6 \%$,he would have received $₹ 72$ more. What was the cost price of the cow?

Arun purchased $30 \, kg$ of wheat at the rate of $Rs. \, 11.50$ per $kg$ and $20 \, kg$ of wheat at the rate of $Rs. \, 14.25$ per $kg$. He mixed the two and sold the mixture. Approximately at what price per $kg$ should he sell the mixture to make $30 \%$ profit? (in $Rs.$)

$A$ shopkeeper sells goods at $10 \%$ loss on cost price,but uses $20 \%$ less weight. What is his profit or loss percentage?

$A$ machine is sold at a profit of $15 \%$. Had it been sold for $Rs\, 540$ more,$24 \%$ would have been gained. Find the cost price.

$A$ pair of articles was bought for $Rs. 37.40$ at a discount of $15 \%$. What must be the marked price of each of the articles?

$A$ shopkeeper sold some articles at $Rs. 35$ per piece and gained $40 \%$. What would be the selling price of each article to earn $60 \%$ profit? (in $Rs.$)