Two points c and D on the same line AB, known as ad = 9 / 5bd, AC = 9 / 5, CD = 4cm, find the length of ab

Two points c and D on the same line AB, known as ad = 9 / 5bd, AC = 9 / 5, CD = 4cm, find the length of ab

C. D two points are on the line AB, AC