For the holiday season of 2017, nearly 59 percent of consumers planned to buy gift cards. According to the National Retail Federation, millennials like to purchase gift cards (Dayton Daily News website). Consider the sample data in the file GiftCards. The following data are given for a sample of 600 millennials: the amount they reported spending on gift cards over the last year, annual income, marital status (1 = yes, 0 = no), and whether they are male (1 = yes, 0 = no). 

a. Develop estimated regression equitation that predicts annual spend on gift cards are given annual income, marital status, and gender. 

b. Test the overall significance at the .05 level. 

c. Test the significance of each individual variable using a .05 level of significance.