What is an expressions that have the same value called

In this item, we are tasked to find a term that refers to an expression that have the same value. For example, an expression 8x+4(x+5)+8 is also equal to 12x+28. Though, the expression is totally different in structure but they have the same value once simplified. The term refer to this expression is called Equivalent Expression.

You need to do x2-x1,y2-y1 and divide it by 2 and you should get (1,-3)