13. Using the information in the table, write and solve an equation to find the number of toppings when you would pay the same amount for Pizza A and Pizza B.
Cheese pizza
Price per topping
$1.50
Pizza A
$10
Pizza B
$12.50
$1.00

So the first thing we do is to multiply the top equation by 3. the reason i want to do this is i notice there will be a 6y on both equations and can possibly add/subtract them. so we get 6y = -3x + 27. adding that and the second equation we get 6x = 27-15 which is 12. divide by 6 and we get 2. ∴ x = 2. substituting 2 into the first equation we get 2y = -2 + 9 which is 7. divide by 2 and we get 7/2. ∴ y = 7/2, x = 2.