Answer:
Retained earnings increases equity because profit that are left undistributed to shareholders form part of investments in the company by the shareholders. This means that the company has invested shareholder's fund in extending its operations.
Step-by-step explanation:
This can also be explained by the following formula:
Assets = Equity + Liability
Assets = (Share Capital + Sale - Expenses - Dividend) + Liability
This equation says that the profits left undistributed, form part of the company's equity. Hence proved that the undistributed profits (Retained Earnings) increases equity of the company.