Since you didn't record in your sales account, it means that
your Trading a/c will have less revenue. Remember, the sale item in
your Trading a/c includes:
Cash sales + Credit sales = Total sales.
Sales = Revenue.
*
If revenue decrease, the profit will also reduce. This is the
positive relationship.
If expense increase, the profit on contrary will decrease. This is
the negative relationship.
*
By how much? $428, because it's the net revenue earned. So there
will be a decrease of profit.
[correct me if there are errors]