- Iron is a kind of element
- Rust is made of iron and oxygen
- Oxygen is a kind of element
- Hence, rust is made of iron and oxygen elements

Therefore, rust is made of iron and oxygen elements
Rust is a compound with the formula Fe_{2}O_{3}. Which elements combine to form rust?
- Iron is a kind of element 
- Rust is made of iron and oxygen 
- Oxygen is a kind of element