A jar contains 0.85 liter of strawberry juice and 0.50 liter of mango juice. Celina poured 0.15 liter of watermelon juice into the jar. She then drank 0.30 liter of the mixture. Part A: Write an expression to represent the total amount of juice left in the jar. (5 points)

Part B: Simplify the expression and identify which property is used in each step. (5 points)