U.S. Treasury Secretary Janet Yellen concluded her three-day working visit to South Africa Friday after holding a series of engagements, which included meetings with President Cyril Ramaphosa and South African treasury and business leaders. As reporter Thuso Khumalo reports from Johannesburg, the key purpose of Yellen's visit was to deepen economic ties and expand investment opportunities as a follow up to President Joe Biden's promises at last month's U.S.-Africa Leaders Summit held in Washington. Yellen also stopped in Senegal and Zambia as part of her 10-day visit.