#### Answer

The current decreases to 90 percent of its original value, to 9 A. The power decreases to 81 percent of its original value, to 972 W.

#### Work Step by Step

Find the resistance of the coffeemaker.
$$Current = \frac{voltage}{resistance}$$
Rearranging to solve for the resistance, we obtain
$$Resistance= \frac{voltage}{current}$$
Put the numbers in from this problem.
$$Resistance= \frac{120 V}{10 A} = 12 \Omega$$
What current will flow when the voltage is cut to 90 percent of 120 V, or 108 V?
$$Current = \frac{voltage}{resistance}$$
$$I = \frac{108 V}{12 \Omega} = 9 A$$
$$Electric \; power = (current) \times (voltage)$$
$$P = (9 A)(108 V) = 972 W$$
Summary: Current and voltage both decreased by 10 percent. The power, which is their product, decreased by 19 percent (because (0.9)(0.9) = 0.81 = 1 - 0.19).