The initial amount of the water is 15 gallons
These are functions that has a leading degree of 1. Given the equation that represents the amount of water remaining after x minutes;
y - 12 = -3(x- 1)
y -12 = -3x + 3
y = -3x +3 + 12
y = -3x + 15
In order to determine the initial amount of water, we will substitute x =0 into the function
y = -3(0) + 15
y = 15
Hence the initial amount of the water is 15 gallons
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