Solution:
Let "x" be the number of toppings
Given that,
Tony's hamburgers shack sells hamburgers for $2 plus $0.40 for each topping
Therefore,
Cost = 2 + 0.40x ----- eqn 1
Bob's burgers sells hamburgers for $3 dollars plus 20 cents for each topping
20 cents = $ 0.2
Therefore,
cost = 3 + 0.2x -------- eqn 2
For both the cost to be same, eqn 1 is equal to eqn 2
2 + 0.40x = 3 + 0.2x
0.40x - 0.2x = 3 - 2
0.2x = 1
Divide both sides by 0.2
x = 5
Thus, for 5 toppings, cost of tony and bob are same