Answer:
-salt raises the melting point of the ice. Mix ice with salt then put the bottle of cream in the ice-salt mixture to freeze the cream.
Explanation:
-Salt lowers the freezing point of water in a phenomena called freezing point depression.
-Mix the ice with salt to lower it's freezing point below zero.
-Now, put the bottle of cream in the mixture, the ice will freeze faster due to the lowered temperature.