The definite article and noun agreement should be CORRECT
Si puedes mezclarla
No , no la puedes mesclar
Or also
Si la puedes mezclar
A Paulina no le gusta trabajar = falso
Paulina likes working, but she doesn't think the class is beneficial to her, and other concerns she has is that there are not enough computers for all the students and the person in front of her talks too much
I can give you help for number 2. Not that i don't know the rest but it's best that you learn by what you can do. The example they give you for part B (la obra fue larga) means, the work was long. They give you an image to show people working. For the others, they give you an idea on what to write, so they can be just about anything, so there's no right or wrong. I'll give you an example for number 2; they show you books. It could be words that are hard or HW. For example: La tarea fue dificil. If there is any other you are still stumped on, let me know so i can help.
