The Four Properties of Equality

If 𝐴=𝐵, then 𝐴+𝐶=𝐵+𝐶

If 𝐴=𝐵, then 𝐴−𝐶=𝐵−𝐶

If 𝐴=𝐵, then 𝐴⋅𝐶=𝐵⋅𝐶

If 𝐴=𝐵, then 𝐴𝐶=𝐵𝐶, where 𝐶 is not equal to zero.