Answer:
It means that above 0 degrees Celsius the water does not freeze, whereas 0 degrees are freezing teperatures of water.
Step-by-step explanation:
Water freezes at 0 degrees Celsius, but the freezing temperature can be lowered by adding salt to the water. A student discovered that adding half a cup of salt to a gallon of water lowers its freezing temperature by 7 degrees Celsius. What is the freezing temperature of the gallon of salt water?
0° - 7° = -7°
