Answer
$16$; $8$; $4$.
Work Step by Step
Number of teams remaining after a particular round is $\frac{1}{2}$ times the number of teams remaining after the previous round.
This implies that the number of teams remaining after the $n$th round is $\frac{1}{2^n}a$, where $a$ is the number of teams in the beginning.
In our case $a=128$. The number of teams remaining after the third round is:
$\frac{1}{2^3}\times128=16$
After the fourth round:
$\frac{1}{2^4}\times128=8$
After fifth round:
$\frac{1}{2^5}\times128=4$
