it helps you because you can divide the bottom to the top or vice versa or you can divide x and y
True a function is a rule that assigns each input exactly one output.
That is not enough information.
If you look at the graphic, diagonal BD (along with point E), can be moved up and down the long diagonal and the two diagonals will still have the same length. You need to state additional information.
So you would have -20C. Then you would multiply that by 1.8 which would give you -36 then you would add 32 which gives you your final answer which is -4 F