This is an example of the "commutative" property.
commutative property of addition
Associative Property of Multiplication
It is the additive property of equality, as the additive property of length, as applied to adjacent or parallel line segments.
I don't know what a 'mathematical' sentence is. I'd prefer to call it an English sentence that describes a mathematical process and makes a statement concerning mathematical matters.
It is the property that equals plus equals are equals.
This is an example of the "commutative" property.
Addition is commutative.
commutative property of addition
Substitution property.
The mathematical statement 31 plus 21 equals 52 as a total.
Associative Property of Multiplication
It is the additive property of equality, as the additive property of length, as applied to adjacent or parallel line segments.
I don't know what a 'mathematical' sentence is. I'd prefer to call it an English sentence that describes a mathematical process and makes a statement concerning mathematical matters.
because its zero
It is the property of commutativity.
It is the additive identity property of zero. For any value, a + 0 = a.