Ok let me help you with these questions:
a. The Percentage excess reserve formula can be expressed as (excess reserve required)/(total reserve). We know the required amount is $100B less than $240B, or $140B, and that the total reserve is $1000B, thus we can do it like this
Percentage excess reserve= (140B)/(1000B) = 14%
b. We can use the same formula but using 240 instead of 140, So it would be:
Percent excess reserve = (240B)/(1000B) = 24%
c. If the existing excess reserves were eliminated the deposits would be locked in the financial institutions and not be able to be removed until additional deposits were made