Answer and Explanation:
Proof by the using contradiction:
Let us assume that it isn't the situation and the statement is incorrect. Accordingly, the quantity of leaves in a subtree is either not as much as [tex]\frac{L}{3}[/tex] or more noteworthy than [tex]\frac{2L}{3}[/tex]. Presently, on the off chance that we consider the subtree with number of leaves greater than [tex]\frac{2L}{3}[/tex] leaves, we can say that there exists a subtree of the subtree referenced before that has more than [tex]\frac{4L}{9}[/tex] leaves. Be that as it may, once more, [tex]\frac{L}{3}\leq \frac{4L}{9} \leq \frac{2L}{3}[/tex] thus the first explanations holds.
