C=2•pi•r because C= pi•d and d=2•r
The percentage of increase is 100%. Let me know if you need an explanation.
Can you repost this with a picture please ?
-40 +2n= 4n -8(n+8)
-40 +2n= 4n -8n -64
-40 + 2n = -4n -64
2n = -4n -64 +40
2n=-4n-24
2n+4n=-24
8n=-24
N= -3
Answer is n equals -3