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 :)
Based off of what I can see in the photo (its too blurry to know for sure) and what I think you're asking:
The angle of a triangle always adds up to 360degrees, so base it on that and the acute and obtuse angles and get the degrees from there, the angle would be those degrees you find or <10, 5, 4 (what I assume is a 5)
