Final answer:
The gross income for the month when adding up the income amounts: $900, $1,300, $400, and $1,100, totals to $3,700.
Step-by-step explanation:
To calculate the gross income for the month, you need to add together all sources of income. In this scenario, we have four amounts to include: $900, $1,300, $400, and $1,100. To find the total gross income, simply add up these figures:
$900 + $1,300 + $400 + $1,100 = $3,700.
Therefore, the gross income for the month equals $3,700.