What equation shows how rate depends on concentrations of reactions?

The equation is called the rate law equation. For the reaction aA+bB =>cC+dD the rate law would be rate = k[A]^m[B]^n where k is the rate constant and m and n are the "order" with respect to each reactant. m and n must be determined experimentally and may or may not be the same as the coefficients a and b.