Can somebody help me understand these questions?

How are algebraic expressions evaluated using substitution?

The statements below can be used to prove that the triangles are similar. ? △abc ~ △xyz by the sss similarity theorem. which mathematical statement is missing? ∠b ≅ ∠y ∠b ≅ ∠z

Y< 2x-3 y? mx+3 which value of m and which symbol result in the system of inequalities shown above having no solution? a) m=-2; > b) m=-1/2; < c) m=2; > d) m=2;