I think you did very well, not completely correct on all of them however. here is my analysis:

for questions 1-4, you got all the (b)'s and (c)'s incorrect, but judging by your performance in part (a), i'm sure it was becuase you misread the questions.

Incorrect:
you got two and a half questions incorrect. what's with the half? allow me to explain.

for question 8, you had the wrong answer. why is it wrong? hint: c is a constant

for 10 part (a), you had 5x^4 in the bottom, when you should have 5y^4. this is just an honest mistake i think, since you got the right answer in part (b) (which was really the same thing as part (a) according to how you did it). this is the half incorrect i was talking about.

question 12 is also wrong. recheck your work to see if you can spot the error

Rewrite:
the following are not questions you got wrong. you were correct, however, there were more efficient ways to write your answers, try to identify what i did to go from your answers to "better" answers.

3(a)

Your answer: y' = x^-2/-y^-2

Better answer: y' = - y^2/x^2

4(a)

Your answer: y' = (-1/2)x^(-1/2)/(1/2)y^(-1/2)

Better answer: y' = - y^(1/2)/x^(1/2) = - sqrt(y)/sqrt(x)

5

Your answer: y' = -2x/2y

Better answer: y' = -x/y

6

Your answer: y' = -2x/-2y

Better answer: y' = x/y

13

Your answer: y' = 4sin(x)sin(y)/4cos(x)cos(y)

Better answer: y' = tan(x)tan(y)

for 1-4, i wouldn't really worry about part (c), part (a) and (b) have the stuff you need to be practicing