How do I make jpegs to this spec ??

[Stephen7372]

How do I make jpegs to this spec ??

Here is the requirement pics with these specs: 170dpi with the longest length of the pic at 30cm; saved as a no. 5 jpeg (the compressed file size should be between
500 and 800k).

I have photoshop

 

[Mindriot]

What about image -> image size and change the document size and dpi, then click save and it will ask you about compression settings