Question

At 3 P.M., the temperature was 9°F. By 11 P.M., it had dropped 31°F. What was the temperature at 11 P.M.?

Answer 1

`-28^circF`

Explanation:

`9^circF=9F^circ " above zero"`
If the temperature dropped `31F^circ`
then the new temperature is
`color(white)("XXXX)9F^circ`
`color(white)("XXX")underline(-31F^circ)`
`color(white)("XXX")-28F^circ "above zero"`
or simply `-28^circF`

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This is perhaps being picky but the question should read:
"...it had dropped `31F^circ`" and not "`31^circF`"
`31F^circ` is a distance or amount of change in temperature.
`31^circF` is a specific temperature or location on the Fahrenheit scale.