Explanation:
Let the number of toppings be y
If cheese pizza at Chicago's Deep Dish pizza costs $7 and each topping costs an additional $0.75, the total amount of the dish pizza will be expressed as;
$7 + $0.75y ..... 1
Also, if a cheese pizza at Brooklyn's cost $12 and each topping costs an additional $0.50, then the total cost of cheese pizza will be;
$12 + $0.50y ........ 2
If the two pizzas cost the same, then equation 1 will be equal to equation 2 as shown;
7+0.75y = 12+0.50y
Make y the subject of the formula to generate the required equation for y:
0.75y-0.50y = 12-7
0.25y = 5
divide both sides by 0.25
0.25y/0.25 = 5/0.25
y = 5/0.25
y = 20
Hence the equation that represents how many toppings, y, must be added so that the two pizzas cost the same is y = 5/0.25 and the number of toppings added is 20.