Tysm for all your help Here is a crown and points. contest the first answer will get a mark

In the field of thermodynamics, rankine is the unit used to measure temperature. one can convert temperature from celsius into rankine using the formula c= r/1.8 - 273, what is the temperature in celcius corresponding to r degrees rankine.

Find an equation of the line perpendicular to the graph.

Any is very appreciated! (picture is provided below)not sure how to do this at all won't lie