I'm pretty sure it would be y=2x+9
I have a question just so u wont get it wrong and to see if im right but are you trying to get the missing number ???
what i did to get my answer was 13*6*6 because the whole circle is 12 and so i got 468.
HE was planning to pay 30$ but it ended up as 60$ so in that case it´s 42$.
