Step-by-step explanation:
1) for t = 0, the initial value is -0.45 gal. which is funny. when it is really cold, do people add water to the tank somehow instead of consuming water ?
so I guess, that system is really reliable with values greater than 0.
0.0875t = 0.45
t = 5.142857143...°
so, I guess, 6° is the lowest reasonable value for this function.
2) as for any line function, the slope is the rate of change.
so, 0.0875 gal more per 1 degree more in temperature.
3) t = 90
w = 0.0875×90 - 0.45 = 7.425 gal
