Answer:
15
Step-by-step explanation:
The parallel lines divide the transversals proportionally.
The green length = 24 - c , then
[tex]\frac{24-c}{20}[/tex] = [tex]\frac{c}{12}[/tex] ( cross- multiply )
12(24 - c) = 20c ← distribute left side
288 - 12c = 20c ( add 12c to both sides )
288 = 32c ( divide both sides by 32 )
9 = c
Then
green length = 24 - 9 = 15