The contents of Reggie’s backpack weigh 20ib. Eight tenths of the weight is from his textbooks. How much do his textbooks weigh? (please show how you got the answer?

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