According to my professor, this is how I should solve Question #1: How much does this bank actually have in reserves? There are only 2 numbers that, when added together, equal actual reserves. Look up the definition of actual (total) reserves in your text. It's in one of the margin definitions. Once you've done that, calculate how much the bank is required to hold in reserves. 20% x what? (transaction deposits - $70,000). Once you have that, subtract required reserves from actual reserves to get excess reserves. Multiply excess reserves by the multiplier and you have the maximum amount the money can expand.
But I got something completely different number, so then my professor said:
Not quite. Actual (total reserves) = vault cash + deposits at the Fed (see Reserves in the margin of page 348 in your textbook).
$6,000 in vault cash + $12,000 on deposit at the Fed = $18,000 total reserves.
(.2)(transaction deposits) = (.2)($70,000) = $14,000.
Excess reserves = $18,000 - $14,000 = $4,000.
Multiply excess reserves by the multiplier to determine the maximum amount the money supply could expand.