I am not able to find any time and work word problems that are related to unit of work , and rate of work and number of days to complete a job etc,. there use to be a good collection of these lessons and with the new interface, the search not showing any time and work problems , can some one help please 

Hello Brianna & Siva! My name is Lisa Krueger and I am a Khan Academy Ambassador teaching in Chicago. I did a search for 'unit of work' in KA and several results, I've included a link to what I think you are looking for it was under Pre-Algebra: Ratios, rates, proportions; but if I am wrong please let me know. I will also ask the KA staff if they know of an easier way to access what you are looking for. Hopefully this helps and thank you for posting. 

https://www.khanacademy.org/math/pre-algebra/pre-algebra-ratios-rates/pre-algebra-rates/v/introduction-to-rates 

Where is the best place to learn about and practice translating word problems into equations?

Hello Rylie! I would start with Writing basic algebraic expressions word problems and work through the 5 items in that section. Please let me know if you have any further questions, comments, or suggestions. Thank you for posting.