A liter of water weighs a kilogram so 15 mg/kg = 15 ppm on a mass over mass basis. If that is the flavor of ppm you want, done. But ppm can also be computed on a volume basis, molar ratio, etc. It is better tio use a clear form with units that identifies the basis such as mg/kg.
Serena Williams knocked off Lucie Safarova in the final of the women's draw at the French Open, and Bovada has her listed as the clear favorite on the odds to win Wimbledon this year; Williams sits as the 7/4 chalk on those betting lines.
Wimbledon 2016: Venus and Serena Williams win doubles. Read more about sharing. Serena Williams won her second Wimbledon title within five hours with victory in the women's doubles alongside sister Venus. The pair won 6-3 6-4 against Timea Babos and Yaroslava Shvedova to claim their sixth Wimbledon doubles title and 14th doubles Grand Slam.