If the price of eraser is reduced by $25\%$, a person can buy $2$ more erasers for a rupee. How many erasers are available for a rupee ?

When the price of fans was reduced by $20\%$, the number of fans sold is increased by $40\%$. What was the effect on the sales in rupees?

After reducing the salary of a man by $50\%$, it is increased by $50\%$. The loss is:

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Fresh grapes contain $80\%$ water while dry grapes contain $10\%$ water. If the weight of dry grapes is $250 \mathrm{kg}$, what was its total weight when it was fresh?

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The length of a rectangle is increased by $60\%$. By what percent would the width have to be decreased to maintain the same area?

In an election between two candidates, one got $55\%$ of the total valid votes and $20\%$ of the votes were invalid. If the total number of votes was $7500$, the number of valid votes that the other candidate got was:

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The length and breadth of a square are increased by $30\%$ and $20\%$ respectively. The area of the rectangle so formed exceeds the area of the square by :

A papaya tree was planted $2$ years ago. It increases at the rate of $20\%$ every year. If at present, the height of the tree is $540 \mathrm{cm}$, what was it when the tree was planted?

In an examination, there were $2000$ candidates, out of which $900$ were boys and the rest were girls. If $32\%$ of the boys and $38\%$ of the girls passed, then the percentage of failures is _____.