Given that there are two points CD on the line AB, AC = 1 / 3 BC, ad = 5 / 4bc, CD = 7 cm, find the length of the line ab Ad equals 4 BD out of 5

Given that there are two points CD on the line AB, AC = 1 / 3 BC, ad = 5 / 4bc, CD = 7 cm, find the length of the line ab Ad equals 4 BD out of 5

AB=36
Let the whole line segment be divided into 36 parts, then AC: BC = 9:27, ad: BD = 16:20
CD = ad-ac = 7 (CD accounts for seven parts of the whole line segment)
7 / 7 = 1 (each segment is 1cm)
36*1=36