How to identify the property that justifies the statement : If 4x - 3 = 7, then 4x = 10.

Answer 1

You might see this as a use of the existence of inverses 3 + (-3) = 0.

When I was young and first learning geometry, we would write: "='s + ="s = ="s" on the right side of a so-called 2 column proof.

My friend Dick (retired math teacher) calls it the "Golden Rule of Equations": In order to maintain equality, whatever you do on one side of an equation, you must do on the other side as well.

A "property"...I don't know!