Final answer:
The actual net income for the month is -$30. Less money could have been put into savings or less money could have been spent on food to keep the actual net income at a positive value.
Step-by-step explanation:
The actual net income for the month is -$30. This means that expenses exceeded income and resulted in a negative net income. To keep the actual net income at a positive value, changes could have been made to either reduce expenses or increase income. For example, less money could have been put into savings or less money could have been spent on food to reduce expenses and increase the net income. Therefore, the correct answer is option d, both a and c.