Not sure what you're asking. are you wanting to solve 5 ( a - b), where b equals those two things listed below? If that's the case, I can definitely help. If not, please clarify.
Answer: 
Step-by-step explanation:
Let the angle of depression be x.

Answer:
2
Step-by-step explanation:
The trick here is to reduce each of the bases to lowest form first
Answer:
1) 0.5
2)-2
3)-23
Step-by-step explanation:
1) -3×1=-3
-3+2.5= 0.5
2) -3×1.5=-4.5
-4.5+2.5= -2
3) -3×8.5=-25.5
-25.5+2.5=-23