Cedric and Josh both ordered the same size pizzas at Marco’s Pizzeria; however, they ordered different toppings. Marco’s charges an additional fee for toppings, but all toppings cost the same. Cedric got pepperoni, banana peppers, and black olives on his pizza for a cost of $15.74. Josh ordered mushrooms and eggplant on his pizza and paid $14.49. Using this information, write an equation for the cost of a pizza, C, as a function of the number of toppings, t ordered.

Let
C---------> the cost of a pizza
t----------> number of toppings

we know that
$15.74-3t=$14.49-2t
15.74-14.49=3t-2t-------------> t=1.25

the cost of one topping is $1.25
and the cost of one pizza without topping is
15.74-3*1.25--------> $11.99

then
an equation for the cost of a pizza, C, as a function of the number of toppings, t ordered is
C=11.99+1.25t

the answer is 
C=11.99+1.25t