confidence interval

Analytics Tech. Inc. has developed the following sales forecasting model to help predict revenue (in thousands) in regards to how much is spent on advertising.
Revenue = 123.5 + 2.3(Dollars), with a standard error of the estimate to be 31.2.
7)
How much revenue would you see if no money was spent on advertising? How much revenue would you see if $250 was spent on advertising?
What would the range (prediction/confidence interval) of this forecasting using two standard errors of the estimate? Assuming that you spent $250 on advertising.