Chick-fil-a has a special going on where you get 2 packs of chicken nuggets for $6.00 and each additional pack is $2.50.

a) Write an equation in slope-intercept form that models the cost based on the total number of packs of chicken nuggets purchased. (Assume at least 2 packs will be purchased)

b) How much would it cost if you bought 6 packs of chicken nuggets?