Answer:
Adding salt to water raises the freezing (and melting) point of water (to below 0 °C or 32 °F). Salty water will freeze at a lower temperature than pure water, thus making it take longer to freeze than the same amount of pure water.
See the Related Question to the left for more information about how to solve for the exact change in freezing point.
i think that yall are right but i think it takes longer becase the salt gose to the bottem and sits there causing it not to freeze for a while