1. **State the problem:** We are given the market demand and supply functions for a digital service: $$Q_d = 120 - 3P$$ $$Q_s = 30 + 2P$$ We need to find the equilibrium price and quantity where demand equals supply. 2. **Formula and rule:** At equilibrium, quantity demanded equals quantity supplied: $$Q_d = Q_s$$ So, $$120 - 3P = 30 + 2P$$ 3. **Solve for price $P$:** Move terms involving $P$ to one side: $$120 - 3P = 30 + 2P$$ $$120 - 30 = 2P + 3P$$ $$90 = 5P$$ Divide both sides by 5: $$\cancel{5}P = \frac{90}{\cancel{5}}$$ $$P = 18$$ 4. **Find equilibrium quantity $Q$:** Substitute $P=18$ into either demand or supply equation: Using demand: $$Q_d = 120 - 3(18) = 120 - 54 = 66$$ Using supply: $$Q_s = 30 + 2(18) = 30 + 36 = 66$$ Both match, confirming equilibrium quantity is 66. **Final answer:** The equilibrium price is $18$ and the equilibrium quantity is $66$.