Carlos Martin received a statement from his bank showing a balance of $56.75 as of March 15th. His checkbook shows a balance of $87.37 as of March 20. The bank returned all the cancelled checks but two. One check was for $5.00 and the other was for $13.25. How much did Carlos deposit in his account between the March 15 and the March 20?

87.37 - 56.75 = 30.62

5. + 13.25 = 18.25
30.62 - 18.25 = 12.37

To find out how much Carlos deposited in his account between March 15th and March 20th, we need to calculate the difference between the checkbook balance and the bank statement balance.

First, let's subtract the check amounts not returned by the bank from the checkbook balance:

$87.37 - $5.00 - $13.25 = $69.12

Next, we compare the adjusted checkbook balance with the bank statement balance:

$69.12 - $56.75 = $12.37

Therefore, Carlos deposited $12.37 in his account between March 15th and March 20th.