Help please, im confused

Solve |2x - 5| = 4 if anyone could , that would be great

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?

Ireally don't understand this, i'm really an idiot but i want to know how to figure this out. !