You don't need a reference clip for these questions. I already posted the solution file to the questions, which is self-explanatory. Also, I wrote examples akin to practice problems. 

For instance, the solution for 13

25x^3y^2=5 5 x x x y y 

As I mentioned in the lecturenote p.16, you just replicate exact same process of what is being written.

Also, for the questions from 21 to 24, you are using the distributive property, which I also wrote in the lecturenote p.17.

If you just try to simulate the example above, you can find out the answer. For instance, 3x^2-15x=3x(x-5).

So far, more than thousands of students took this lecture, and nobody requested for reference clips, and I believe it is because it was self-explanatory by lecturenotes. I recommend reading the lecturenote before you try solving practice problems.

Thanks