In AC circuits the capacitance and inductance are involved. Mostly the inductance and capacitance of components are given and you are required to calculate the values of reactance from data. After this, the reactance can be solved with the resistance and can be used with the symbol of j in numerical. This AC Formula Sheet provides formulas for Capacitive and Inductive reactance calculations, Impedance of circuits and application of Ohm’s Law in AC.
You can simply follow the sheet or can learn the reactance concepts in detail from this tutorial: