If $X = 600$ and $Y = 800$,then $X$ is how much percent less than $Y$?

In an election between two candidates,$10 \%$ of the voters did not cast their vote. $10 \%$ of the votes polled were found invalid. The successful candidate received $54 \%$ of the valid votes and won by a majority of $1620$ votes. The total number of voters enrolled on the voter's list was:

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:

The price of sugar is reduced by $2 \%$. How many $kg$ of sugar can now be bought for the money which was sufficient to buy $49$ $kg$ of sugar earlier?

$405$ sweets were distributed equally among children in such a way that the number of sweets received by each child is $20 \%$ of the total number of children. How many sweets did each child receive?

Find a single equivalent increase,if a number is successively increased by $10 \%$,$20 \%$,and $25 \%$. (in $\%$)