The rate of the reaction at given time for given reactant concentration data has to be calculated.
Rate of a reaction: It represents the speed at which a chemical reaction runs. How much concentration of substrates (reactants) consumed and how much concentration of targets (products) formed in a unit of time is said to be rate of reaction.
Rate law: It is an equation that related to the rate of reaction to the concentrations or pressures of substrates (reactants). It is also said to be as rate equation.