$x \%$ of $y + y \%$ of $x = ?$

If $A = x \%$ of $y$ and $B = y \%$ of $x$,then which of the following is true?

The price of sugar has fallen by $10 \%$. How many quintals can be bought for the same money which was sufficient to buy $18$ quintals at the higher price?

If "basis points" are defined so that $1 \%$ is equal to $100$ basis points,then by how many basis points is $82.5 \%$ greater than $62.5 \%$?

$A$ set $A$ consists of integers $27, 28, 30, 32$ and $33$. If an integer $K$ is included,the average of set $A$ will increase by $30\%$. What is the value of integer $K$?

The price of cooking oil has increased by $25 \%$. The percentage of reduction that a family should effect in the use of cooking oil,so as not to increase the expenditure on this account,is (in $\%$)