Ordered pairs satisfy the equation 3y−9x=9

Can you me find the missing length. i attached an image.

Which of the following equations are equivalent to -2m - 5m - 8 = 3 + (-7) + m? -15m = -4m -7m - 8 = m - 4 -3m - 8 = 4 - m m - 4 = -7m - 8 -8 - 7m = -4 + m -8 - 3m = 4 - m

If you prove that ∆wxz is congruent to ∆yzx, which general statement best describes what you have proved?