I think the answer is 17. The scale is going up by two.
You tell me if this makes sense to you.
It's 47 years from 1970 to 2017 so you would need to multiply 7% by the 47 years.
So: 0.07x47= 3.29
Now you should add your new price to your original price: $3.29+$0.35= 3.64
So it should cost $3.64 now. Yes that does seem kind of low but that's how you do it.
I hope this helps :)
