fisrt we are going to find the delivery fee. for this we can use the information in teh table to have two equations with two incognitas:
With the second row we can have, where p is the variable for the pizza and f is the variable of the fee:
This ecuation says that one pizza plus the fee is going to be $20. now with the 3 row we can made the same procedure:
Now we have two incognitas and 2 equations. for solving this I solve the first equation for p:
and I replace p in the second equation:
So the fee is $8.
For the price or the pizza we can use any of the two equation above, and replace the value of the fee. In this case I use the first equation:
Now for the final question: ¿How many pizzas can someone order if they had 120 dollars?
first we can take out the cost of the fee:
And the customer will have 112 dollar for the pizzas, so we can divide the total amound of money by the unitary cost of the pizza:
So he will be able to buy 9 pizzas.