I will help but what is the question? to me it looks like you just gave us the details
For the table 0.2 would be (1/5) 0.5 would be (1/2). And 0.7 would be (7/10).
For number 2 I would say the denominator changed each time
3/4 + -5/8
---Find a common denominator
6/8 + -5/8
---Simplify
1/8
Hope this helps!