$A$'s salary is $40 \%$ of $B$'s salary,which is $25 \%$ of $C$'s salary. What percentage of $C$'s salary is $A$'s salary?

In an examination,$70 \%$ of the candidates passed in English,$80 \%$ passed in Mathematics,and $10 \%$ failed in both subjects. If $144$ candidates passed in both,the total number of candidates was:

In a History examination,the average for the entire class was $80$ marks. If $10 \%$ of the students scored $95$ marks and $20 \%$ scored $90$ marks,what was the average marks of the remaining students of the class?

In a mixture of milk and water,the proportion of water by weight was $75 \%$. If $15 \text{ gm}$ of water is added to $60 \text{ gm}$ of this mixture,what will be the new percentage of water by weight (in $\%$)?

Sashi has $Rs. 90000$ with him. He purchases a mobile,an iPad,and a laptop for $Rs. 15000$,$Rs. 13000$,and $Rs. 35000$ respectively and puts the remaining money in his bank account which pays $15 \%$ per annum compound interest. After $2$ years,he sells off the three items at $80 \%$ of their original price and also withdraws his entire money from the bank by closing the account. What is the total percentage change in his assets (in $\%$)?

Aman gave $40 \%$ of the amount he had to Rohan. Rohan in turn gave one-fourth of what he received from Aman to Sahil. After paying $₹ 200$ to the taxi driver out of the amount he got from Rohan,Sahil now has $₹ 600$ left with him. How much amount did Aman have?