Chemistry Lab Help!! PLS!!?

A sample of hydrated salt weighs 3.8526g before it is heated. After heating to a constant mass the sample weighs 2.3658g. Determine the mass percent of water in the sample. ..so I know to calculate mass percent is dividing mass of the water by the molar mass of the hydrate. then x100, but what do I do with the two... show more A sample of hydrated salt weighs 3.8526g before it is heated. After heating to a constant mass the sample weighs 2.3658g. Determine the mass percent of water in the sample.

..so I know to calculate mass percent is dividing mass of the water by the molar mass of the hydrate. then x100, but what do I do with the two different weights?
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