Its is two since you take out the decimals then divide regularly
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 :)
I think ordered pair D would be the correct one