Well, for any prism, it is the lateral area + the area of two ends.
the first one is -11,-5,2,6,19
Same question and answer as yours!
1) Given
2) Adding segments AB and BC together gives AC (Addition postulate, not too sure about the terminology)
3) Segment Addition postulate
4) Segment Addition postulate(Knowing that AC=BD, the distance between BC and CD add up to BD, shown in #3. AB and BC add together to give AC)
5) Subtraction property of Equality
Hope I helped :)