Oh yes... Wonderful Proportions. There are ways to do proportions but this is how I learned how to do them :
PART %
=
WHOLE 100 That is the formula. I'm not sure of an example but I hope it helps
Answer:
the sequence is by -5
therefore the next numbers are
-13,-18,-23,-28
I cant explan but i think only rectangular prisms.
1. Move the negative sign to the left.
- 
*-50
2. Use this rule: 
=
-
3. Simplify - 
4. Move the negative sign to the left.
-(-950x/8)
5. Simplify 950x/8 to 475x/4
6. Remove parentheses.
