If the price of gold increases by $30 \%$,find by how much the quantity of ornaments must be reduced so that the expenditure may remain the same as before?

$A$ shopkeeper undertakes to supply $2000$ tables at $Rs. 1725$ each. He estimates that if $10\%$ are defective,which will be sold at $50\%$ of the original price,then the profit will be $15\%$ on his whole outlay. When the tables were supplied,$70\%$ of the tables were found defective. What loss did the shopkeeper incur?

In a motor of $120$ machine parts,$5 \%$ parts were defective. In another motor of $80$ machine parts,$10 \%$ parts were defective. For the two motors considered together,the percentage of defective machine parts was (in $\%$)

$25 \%$ of $25 \% = ?$

In a class of $80$ students,each student got sweets that are $15 \%$ of the total number of students. How many sweets were there?

Aditya's salary is $80\%$ of Amit's salary and $120\%$ of Rajiv's salary. What is Amit's salary if Rajiv's salary is $30,000$ (in $,000$)?