Answer
The power is: $30\ W$
For the other element, the power is: $-60 \ W$
Work Step by Step
We know the following equation for power in both cases:
$P = -VI$
Where V is the voltage, P is the power, and I is the current. Thus, we find:
$P = -(-15V) \times (2A) = 30 W$
And, in case two:
$P = -(20V) \times (3A) = -60 W$
Note, when power is positive, the element is taking in energy, while when power is negative, the element is giving off energy.
