a. Using a simple three-month moving average, what is the forecast for September? (Round your answer to 2 decimol places.) b. Using a weighted moving average, what is the forecast for September with weights of 0.20,0.30, and 0.50 for June. July, and August, respectively? (Do not round intermediote colculations. Round your answer to 2 decimal ploces.) c. Using single exponential smoothing and assuming that the forecast for June had been 135, forecast sales for September with a smoothing constant a of 0.30. (Do not round intermediate calculations. Round your answer to 2 decimal places.)