Final answer:
The trend equation for forecasting using the least-squares regression method is ŷ = a + bx, where ŷ represents the predicted value, a represents the y-intercept, b represents the slope, and x represents the input variable.
Step-by-step explanation:
The trend equation for forecasting using the least-squares regression method is given by ŷ = a + bx, where ŷ represents the predicted value, a represents the y-intercept, b represents the slope, and x represents the input variable. In the given equation, ŷ-173.51 + 4.83x, the y-intercept is -173.51 and the slope is 4.83. To use this equation for forecasting, plug in the desired value of x and solve for ŷ.