Ineed on an original three paragraph essay! the prompt is "if the president signs a free trade agreement between the united states and brazil what effects would this have on prices for food, housing, and oil? "

Free Trade Agreements like Tariffs and anti-competitive acts effect different groups within America and the trading partners. 

Artificial barriers to free trade happen to cause odd effects to supply and demand models. They add additional processing delays and cost to enforce the rules and regulations. 

Workers and companies in both countries are subject to the completion for workers and companies who will do the work for less money or who can do it better. To get workers that would work for less they hired lots of immigrants. So markets for goods open in Brazil for US products and and markets in US open for Brazil. Also, Canada and Mexico now have to compete in US markets with Brazil's products. 

One area that makes the competition unfair is the pollution and labor standards in the US. For example we see the Brazil's oranges have a chemical that is not allowed in the US. Countries like Brazil allows allow children to do work that children in US are protected from. some foreign countries allow slaves and prisons to make goods. The US and Canada cannot compete against these immoral and illegal practices. 
Alos is Mexico and Brazil, toxic wastes are just dumped into rivers and land fills, poisoning the seas and people.