$65 \%$ of $? = 20 \%$ of $422.50$

The price of cooking oil has increased by $15 \%$. 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:

If the height of a triangle is decreased by $40 \%$ and its base is increased by $30 \%$,what will be the effect on the area?

The population of a town was $160000$ three years ago. If it increased by $3 \%$,$2.5 \%$,and $5 \%$ respectively in the last three years,then the present population is:

$A$ student has to secure $15\%$ marks to pass the examination. If he gets $80$ marks and fails by $70$ marks,find the maximum marks set for the examination.

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