Using bank reconciliation to determine cash receipts stolen

Alaska Impressions Co$.$ records all cash receipts on the basis of its cash register tapes. Alaska Impressions discovered during October $20Y3$ that one of its sales clerks had stolen an undetermined amount of cash receipts by taking the daily deposits to the bank. The following data have been gathered for October:

Cash in bank according to the general ledger

$$11,680$

Cash according to the October $31,20$Y$3,$ bank statement

$13,275$

Outstanding checks as of October $31,20Y3$

$3,670$

Bank service charge for October

$40$

Note receivable, including interest collected by bank in October $,2,100$

No deposits were in transit on October $31.$

a$.$ Determine the amount of cash receipts stolen by the sales clerk.

$

b$.$ What accounting controls would have prevented or detected this theft?