How did the early Maya make use of their physical environment?​

They cleared arias to farm and grew a variety of crops including beans, squash, avocados, and maize. They also made good building materials from the trees and plants.

i dont know but i need points

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