The amount of water left is 4/10 gallons
Fractions are written as a ratio of two integers
Given the following parameters
Amount of gallon bought = 8/10 gallons
Amount he drank = 4/10
Determine the amount left
Amount left = 8/10 -4/10
Amount left = 4/10 gallons
Hence the amount of water left is 4/10 gallons
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