Step-by-step explanation:
The equation is given as;
2 A + B + 3 C → Products
The order of the reaction refers to the extent at which the rate depends n the concentration of the reactant.
The order of reaction is experimentally obtained. It can also be obtained from the rate law of the reaction.
If the rate law is given as;
rate law = k [A]²[B][C]³
Then the order is second order with respect to A.