Answer:
COP [Constant of Proportionality or k] = ½
Explanation:
y = kx.
y = dependent variable [vertical].
x = independent variable [horizontal].
y in this case is the gallons and x in this case is the hours.
Therefore
#gallons = 1/2 #hours
y = 1/2x
k = 1/2
____________
This is because at a rate,
the pipe leaks at 1/2 or 0.5 gallons per hour.