Sammy and david were selling water bottles to raise money for new football uniforms. Sammy sold 5 water bottles for every 3 that David sold. Together they sold 160 water bottles. What value does each individual part of a tape diagram represent?

If Sammy sold 5 bottles for every 3 that David sold, then the ratio is 5:3. Now we make a diagram with 8 equal parts and check how much one part represents. It's 20, because 160 bottles / 8 parts = 20 bottles per part.

By the way, if the ratio is 5:3, then Sammy sold 5 * 20 = 100 bottles, while David sold 3 * 20 = 60 bottles.