How has the north american free trade agreement affect mexico?

the perimeter of a triangle is 69 cm. side a is 5 cm shorter than side b. side c is twice as long as side a. find the length of each side. i need to know how to do it in 2 equations.  

equations:

a = b-5

c = 2a

a + b + c = 69

this question shoud be under spanish category, not

a u.s. citizen has to have lived in and been an american citizen for a year or more be for he or she can vote for presidential or country wide elections. they also have to register to vote. if the voting is for state representatives or issues, they have to have lived in that state for one month or more and meet the requirements for country wide elections.