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

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 

Ok here we go ..there are plenty of ways to solve such math problems but we will go for the smartest and easiest ..5x+2y=7  -2x+6y=9we rearrange them into the following ..by multiplying the 1st equation by 2 it becomes 10x + 4y = 14we rearrange it and so it becomes 10x = 14 - 4yas for the second equation we multiply it by 5 and rearrange it so it becomes as to the following ..-10x + 30y = 45rearranging so 10x = 30y -45now 10x equals both 14 - 4y and 30y -45so   14 - 4y = 30y -4531 = 26yy= 31/26 = 1.19 or around 1.2so by now we can calculate x easily as  -2x+6y=9so 2x = 6y -9 = 6 * 31/26 - 9 = -1.84  then x = - 0.92 or around -0.9best luck!