Which theme is best represented in this excerpt?
the people expected of me and i had got to do it i could feel their 2000 wills pressing me forward

The excerpt transmits to the reader a strong  sensation and  decision feeling   produced by the force called pressure.  

Accordingly, the best theme represented in this excerpt is an artist behind the scene.

The artist have to wait in a place where there is a crowd expecting of his/her show. In this kind of situation the artist is under many emotions produced for the encounter with the crowd.

substitute y = 2x - 4 to x + 2y = 12:

x + 2(2x - 4) = 12     use distributive property

x + (2)(2x) + () = 12

x + 4x - 8 = 12     add 8 to both sides

5x = 20     divide both sides by 5

x = 4

put the value of x to the first equation:

y = 2(4) - 4

y = 8 - 4

y = 4

evertheless he ought to be slow to believe and to act, nor should he himself show fear, but proceed in a temperate manner with prudence and humanity, so that too much confidence may not make him incautious and too much distrust render him intolerable.

explanation: