Question

The cost of a large pizza is given by c = 0.50t + 18, where c is the total cost and t is the number of toppings. The cost of a medium pizza is half the cost of a large pizza with the same number of toppings. Write an equation that represents the cost c of a medium pizza with t toppings

Answer 1

The toppings would still cost 0.50 each (since it is just toppings)

The large pizza costs $18 if you do not have any toppings
The medium costs half of the large

18/2 = 9

The medium costs $9 without any toppings, so your new equation will be:

c = 0.50t + 9

hope this helps 

Answer 2

$\bf c=\stackrel{\textit{cost of a large pizza}}{0.50t+18}\qquad \qquad \stackrel{\stackrel{cost~of}{medium~pizza}}{\cfrac{c}{2}}\implies \cfrac{0.50t+18}{2} \\\\\\ \cfrac{0.50t}{2}+\cfrac{18}{2}\implies 0.25t+9$