Cost of the large pizza: $5.99
Cost per extra topping: $0.50
1) If we call the number of extra toppings "x", and "y" is the cost for the pizza, the linear equation that represents this situation is:

Where 0.5x is the cost for the topping (x is the number of them) and 5.99 is added because is the cost just for the pizza.
2) a pizza with pepperoni, onnions and chicken.
That means the pizza has 3 toppings ----> x=3
So we find the value of the cost "y" when the number of toppings is 3 with the linear equation from 1).

How much would a pizza with pepperoni, onions and chicken cost?​ $7.49