I'm not sure if this is right or not could someone also explain why ?

Write a corresponding real world problem to represent 2x - 125=400

Arefrigeration system at your company uses temperature sensors fixed to read celsius (°c) values, but the system operators in your control room understand only the fahrenheit scale. you have been asked to make a fahrenheit (°f) label for the high temperature alarm, which is set to ring whenever the system temperature rises above –10°c. what fahrenheit value should you write on the label

What percent of the circle below is shaded?