A family plan for a cell phone has a monthly base price of $99 plus $12.99 for each additional family member added beyond the primary account holder. Write a linear function to model the monthly cost, C(x) in dollars, of a family plan for x additional family members added. 2 1) C(x)=12.99x +99 2) c(x) = 12.99x-99 3) C(x)=99x-12.99 4) C(x)=99x 412.99