(3)(5)=15,then (3)(5)·4=15·4;this is a mathematical equation/equality since it shows an equal sign and does not consists an inequality symbol.
4>2,then 4+15>2+15;this is a mathematical inequality since the mathematical expression consists of inequality symbol.
5·6=30 and30=3·10,then 5·6=3·10;this is a mathematical equality since it shows an equality sign and not an inequality symbol.
x+y=5 and x=3,then 3+y=5;this is an mathematical equation/equality since it consists of an equality sign.
12=12;this is a simple mathematical equality because it has an equal symbol.
3·4=12 and 12=2·6,then 3·4=2·6,this is a mathematical equation\equality since it has an equality symbol.
Points to remember;
It is an inequality statement if it consists of this inequality symbols;≠,≤,≥,<,>
While,it is an equation or equality if it consist of these one and only symbol =.
Hope it Helps:)