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a. To determine if annual sales are increasing or decreasing, you can look at the coefficient of the linear trend equation. The coefficient of the "t" term (15 in this case) indicates the rate of change of annual sales over time.

Since the coefficient is positive (15), this means that for each year (t) that passes, the annual sales (Ft) are increasing by 15,000 bottles.

b. To predict annual sales for the year 2006 using the equation, you need to substitute the value of t = 2006 - 1990 = 16 into the equation and solve for Ft:

Ft = 80 + 15t
Ft = 80 + 15 * 16
Ft = 80 + 240
Ft = 320

So, the predicted annual sales for the year 2006 are 320,000 bottles.

Keep in mind that this prediction is based on the linear trend equation and assumes that the underlying trend remains consistent. It's important to interpret the results in the context of the specific industry and market conditions.