I’m not an expert at simplifying, so I need help

Which equation results from adding the equations in this system? x+6y=9 and -x+2y=-15

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.

Use the zero product property to find the solutions to the equation (x+2)(x+3)=12