. The temperature on a summer afternoon is 84°F. Define a variable and write an expression to find the temperature after it changes. Then evaluate your expression for a decrease of 14 degrees Fahrenheit. 14 – c; 14 – (–84) = 70; 70°F 84 – c; 84 – (–14) = 98; 98°F 14 + c; 14 + (–84) = 98; 98°F 84 + c; 84 + (–14) = 70; 70°F