Divide all the ratios and compare:
8/12 = 0.666
15/10 = 1.5
2/3 = 0.666
6/9 = 0.666
The one that isn't equivalent is 15 over 10
Yes, most definitely
I hope that this helps!
Answer:
1. use the formula


2. use the formula

3. There is only one at 360 degrees
4. there are 6 rotational symmetries and the number of reflectional symmetries would be 6 as you can see: