1. **State the problem:** Calculate the power delivered by the 180 V source in a series circuit with resistors 15 Ω, 20 Ω, and 25 Ω. 2. **Formula and rules:** Power delivered by a voltage source is given by $$P = V \times I$$ where $V$ is the voltage of the source and $I$ is the current through the circuit. In a series circuit, the current $I$ is the same through all components, and total resistance $R_{total}$ is the sum of individual resistances: $$R_{total} = R_1 + R_2 + R_3$$ 3. **Calculate total resistance:** $$R_{total} = 15 + 20 + 25 = 60\ \Omega$$ 4. **Calculate current $i_1$ using Ohm's law:** $$I = \frac{V}{R_{total}} = \frac{180}{60} = 3\ \text{A}$$ 5. **Calculate power delivered by the source:** $$P = V \times I = 180 \times 3 = 540\ \text{W}$$ **Final answer:** The power delivered by the 180 V source is **540 W**.