equation is what you mean;
e·qua·tion /ɪˈkweɪʒən, -ʃən/ Show Spelled[ih-kwey-zhuhn, -shuhn] Show IPA-noun1.the act of equating or making equal; equalization: the symbolic equation of darkness with death.
2.equally balanced state; equilibrium.
3.Mathematics . an expression or a proposition, often algebraic, asserting the equality of two quantities.
4. Chemistry . a symbolic representation showing the kind and amount of the starting materia
the equation of 2/4 is 1/2, they are of equal value.