XAT 2020 Geometry & Mensuration — Previous Year Question

Two lighthouses, located at points A and B on the earth, are $60$ feet and $40$ feet tall respectively. Each lighthouse is perfectly vertical and the land connecting A and B is perfectly flat. The topmost point of the lighthouse at A is A’ and of the lighthouse at B is B’. Draw line segments A’B and B’A, and let them intersect at point C’. Drop a perpendicular from C’ to touch the earth at point C. What is the length of CC’ in feet?