Sam is ordering pizza. Tony's pizza charges 7 dollars for a large cheese pizza plus 0.75 for each additional topping. Maria's pizza charges 8 dollars for a large cheese pizza plus 0.50 for each additional topping. For what number of toppings will the cost of a large pizza be the same at either restaurant?

let no. of toppings = x

cost of tony's ppizza = 7 + 0.75x

cost of maria's pizza = 8 + 0.5x

according to question:

8 + .5x = 7+ .75x

=> 0.25x = 1

=> x = 4