‼️‼️plz help me, you identify the error the solve the problem correctly

Find the solution of system of equation y= x-4 y=4x+2

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?

If a + b = 4, what is the value of |4 – a| + |4 – b|?