Okay, so I believe I have the answer.

x + y = 180 degrees

x + 24 + 2y = 180

//isolate one variable

x = -24 + 2y + 180 // I moved everything to the right side of x

// I substitute -24 + 2y + 180 for x

(-24 + 2y + y) + 180 = 0 // Wouldn't it be -24 + 2y + y + 180 = 180. Though it wouldn't give me the correct answer.

//combine like terms

3y + 156 = 0

3y / 3 = -156 / 3

y = -52 // I don't know why I got a negative. I might need help getting this clarified.

//So I just plug 52 back into y

x + 52 = 180

x = 128