Final answer:
An increase in inventory and a decrease in the cost of goods sold expense will cause equity to increase, which is recorded as a credit on the right side of a T-account.
Step-by-step explanation:
The statement in the question is correct. An increase in inventory, which is an asset, would be recorded as a debit on the left side of the T-account. At the same time, a decrease in the cost of goods sold expense, which is an equity account, would be recorded as a credit on the right side of the T-account. This means that the statement, 'A decrease in an expense account causes equity to increase,' is true. Increases in equity are recorded as credits on the right side of a T-account.