Final answer:
To obtain 20xx8 cash basis net income, supplies inventory should be deducted and office salaries payable should be added to the accrual basis net income.
Step-by-step explanation:
To convert the financial statements from the accrual basis of accounting to the cash basis, you need to consider the changes in supplies inventory and office salaries payable. When supplies inventory decreases, it means cash was used to purchase supplies, so it should be deducted from the accrual basis net income. On the other hand, when office salaries payable decreases, it means cash was paid to employees, so it should be added to the accrual basis net income.