How do I solve this problem

Question

Students find the weight of an empty beaker is 50 grams. They pour 35 grams of salt water solution into the beaker. They leave the beaker in a warm room until all the water has evaporated. They find the weight of the beaker with the remaining contents is 55 grams.

 

What was the weight of the water in the original salt water solution?

Answer 1

Total mass of solution and beaker is 85 g. When all the water has evaporated we are left with 55 g . Mass of salt is therefore 5 g. Mass of water that evaporated was 85 g - 55 g = 30 g