Which decibel value most closely represents a power decrease from 12 watts to 3 watts?

The decibel (dB) scale represents ratios of power. Just as a +3 dB change means the power doubles, a -3 dB change means the power is cut exactly in half. To go from 12 watts to 3 watts, you must halve the power twice. First, halving 12 watts gives you 6 watts, which is a -3 dB change. Halving that 6 watts gives you 3 watts, which is another -3 dB change. When you combine these two steps, the total change is -3 dB plus -3 dB, equating to -6 dB. Choosing -9 dB is a common error resulting from simple subtraction, which ignores how the logarithmic decibel scale actually works.