The percentage increase in the surface area of a cube when each side is doubled is:

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?

The weights of two iron balls are $3.5 \text{ kg}$ and $7.5 \text{ kg}$. What is the percentage weight of the first ball with respect to the second ball?

Ram scored $30 \%$ marks and failed by $15$ marks. Aditya scored $40 \%$ marks and obtained $35$ marks more than those required to pass. What is the pass percentage (in $\%$)?

In a hotel,$60 \%$ of people had vegetarian lunch,$30 \%$ had non-vegetarian lunch,and $15 \%$ had both types of lunch. If $96$ people were present,how many did not have either type of lunch?

There is a ratio of $5:4$ between two numbers. If $40\%$ of the first number is $12$,then what would be $50\%$ of the second number?