309:4

I’m not sure what “309:4” refers to. Could you share the full problem text or tell me:

• Which course/subject and which book or course module this is from
• The exact problem statement (or a photo/screenshot)
• Any given data or formulas that come with it

If you can paste the problem or describe it (algebra, calculus, statistics, etc.), I’ll walk you through the solution step by step and explain the key concepts.