Complex sentence: After Biya became President, he appointed Nkuete as Deputy Secretary-General of the Presidency on April 13,1983, and Nkuete served in that position until Biya promoted him to the post of Secretary-General of the Presidency on November 21,1986.
Split into simpler sentences: After Biya became President, he appointed Nkuete as Deputy Secretary-General of the Presidency on April 13,1983. Nkuete was promoted to the post of Secretary-General of the Government on November 21,1986.