Answer
If "twice as cold" is taken literally, half the internal energy means the temperature is one-half of the current absolute temperature, which is 273 + 10 = 283 K.
$$T_{new} = \frac{1}{2}(283 K) = 141.5 K$$
Convert the absolute temperature in kelvins to the Celsius temperature scale by subtracting 273, finding $-131.5^{\circ}C$.