Piazzanos Pizzeria has a buy-1-get-1-free special on triple cheese pizzas, and a buy-2-get-1-free special on meat lovers pizzas.  If the standard price for a pizza is $5, how much does it cost, in dollars, to purchase 10 triple cheese and 9 meat lovers pizzas using the special pricing?
Using buy-1-get-1-free pricing, it costs 1*$5=$5 to buy 2 triple cheese pizzas.
At $5 per 2 pizzas, it costs $5/2=$2.5 per triple cheese pizza.
Using buy-2-get-1-free pricing, it costs 2*$5=$10 to buy 3 meat lovers pizzas.
At $10 per three pizzas, it cost $10/3=$3 and $1/3 per meat lovers pizza.
With the buy-1-get-1-free pricing, 10 triple cheese pizzas are 10*$2.5=$25.
With the buy-2-get-1-free pricing, 9 meat lovers pizzas are 9*($3+$1/3)=$30.
In total, for 10 triple cheese and 9 meat lovers pizzas, it will cost $25+$30=$55.