What is the central idea of the sonnet?

the speaker considers his love to be his muse.
the speaker wants his muse to him immortalize his love.
the speaker fears that his love is growing old faster than he would like.
the speaker thinks that his muse is forgetful and lazy and wastes a lot of time.

once upon a midnight dreary, while i pondered, weak and weary,

explanation:

yes yes it does !

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

all you have to do is draw a line and copy what is on the paper