When you rewrite the term so that the coefficient is in front, you rearrange the numbers and variables so that all the numbers are in front and the variables come after that. Then, you multiply all the numbers together to get the coefficient.
So, for example in #8:
(3x)8
3 · 8 · x ------ rearrange to get 3 times 8 times x (all the numbers first and the x last)
24x ------ multiply all the numbers together (3 times 8 = 24)
In this case, the coefficient is 24.
In #9:
(4y)2y
4 · 2 · y · y ---- rearrange to get all the numbers first and the variables last
8y² ---- multiply all the numbers (4 times 2 = 8)
and multiply all the variables (y times y = y²)
In this case, the coefficient is 8.