Could someone help with these 4 stats questions please?

They are about joint distributions.
Q4 onwards please

You may need to ask the University to open up the resource?

What do you mean?

Ah okay, how can I make it so you can see the questions? Printscreening doesn't work.

Its a chaptertutorial.pdf, so not sure what the problem is. You can easily grab a snapshot or ...

I have tried print screening the question and attaching them as an image but neither of those things worked

What doesn;t work specifically. Do you save the screenshots or snapshots as images, then upload or, ... Can you upload to a different image site or ...

I press the print screen button then paste. Nothing comes up. I do the "insert image via url" with the printscreen I took but nothing shows up.

I will copy and paste the questions one at a time.

Q5) Let X and Y be independent uniform(0,1) random variables.
(a) Find the joint density of U = X, V = X + Y .
(b) Find the marginal density of V .


Where do I begin?

They're tutorial questions, so what do you understand / what are you confused about?

I understand the first line. "Joint density" could mean lots of things e.g. joint pdf, joint cdf, etc. The solutions have a "Jacobi matrix" but nowhere has it been explained what this does,why it is there or where it comes from.
I also don't know what marginal density is. It could be one of two things but it doesn't say in the question whether we have discrete or continuous data.