Which addition does the model below represent?

A number line going from negative 5 to positive 5. Negative 1 to positive 3 is highlighted, and 0 to positive 3 is highlighted.
3 + (negative 1)
3 + 4
3 + (negative 4)
3 + 1

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.