We know that
• They drink 3,600 cups in a day at 0°F.
,
• The consumption decreases 120 cups each degree.
Since consumption decreases, 120 must be negative.
Also, the constant ratio for change is 120 because that's the variation, this number must be the coefficient of temperature.
Additionally, the initial condition is 3,600 cups, that is, the independent term must be 3,600.-
Therefore, the expression is