Special 1 would be: 8.99 + 5x, with x being the number of additional pizzas you'd order
Special 2 would be: 6x, with x being the number of pizzas you'd order
Lets show what each special would end up costing by putting in 1-3 pizzas in the order
8.99 + 5(0) = 8.99 + 0 = 8.99
6(1) = 6
Note how I put a different number in for the x value in each equation, since keep in mind, the 8.99 is for the first pizza, and the 5 is the number of additional pizzas
8.99 + 5(1) = 8.99 + 5 = 13.99
6(2) = 12
8.99 + 5(2) = 8.99 + 10 = 18.99
6(3) = 18.00
In conclusion, it'd be better to get the $6 deal, assuming you'd only get 1-3 pizzas per order