A gardener plants an orchard with $5776$trees. In each row, there were as many trees as the number of rows. Find the number of rows.

When the price of a radio was reduced by $20\%$, its sale increased by $80\%$. What was the net effect on the sale?

Mr. Chunilal invests $65\%$ of his money in machinery and $20\%$ in the raw material. He is left with $Rs.$$1305$ cash in hand. How much money did he spend (in $Rs.$)?

Find the value of $12\frac{1}{2}\%$ of $400$.