Getting the right cost date from another table

Hi, 

I have 3 tables: one for Parts, second for Production and third for Parts Cost. 

Both are related by the Part ID.

the Parts Cost is having records for the parts' cost that are exists & dated in resolution of one month (cost for part is updated in a frequency of one month), the production has records on a daily basis of course. 

I would like to have a visual that shows the production quantity and its related cost.

Therefore I need to get the latest cost for part prior the production date. 

Can someone please advise how can I get this info? note that I am not so familiar with DAX...