Someone mind helping me, please?

Use the elimination method to find the solution to the system of equations. 2x - 3y = -9 -x + 3y = 6

Solve for n? [tex]z = \frac{3}{4} mn[/tex]

1. 2. ∠b and ∠y are right angles. 3.? 4.? which two statements are missing in steps 3 and 4? ∠x ≅ ∠c △abc ~ △zyx by the sas similarity theorem. ∠b ≅ ∠y △abc ~ △zyx by the sas similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem.