The answer to this question would be: $0 (no increase/decrease in her bank account).
To answer this question you need to list the increase and decrease Sandra cause. The increase happened when she deposited $8.74 money on Tuesday. The decrease happened when she use $8.74 money for lunch on Monday. If you add them together, it will become
Bank account: increase-decrease
Bank account : $8.74 - $8.74= $0
