In Knoxville the temperature rises 4° from 4 PM to 5 PM. Then the temperature drops 7° from 5 PM to 6 PM. What expression represents the change in temperature for Knoxville?

Look at 2%2Ax%2B9=highlight_red%28+25+%29.
Moved these terms to the left highlight_green%28+-25+%29
It becomes 2%2Ax%2B9-highlight_green%28+25+%29=0.
Look at 2%2Ax%2Bhighlight_red%28+9+%29-highlight_red%28+25+%29=0.
Added fractions or integers together
It becomes 2%2Ax%2Bhighlight_green%28+-16+%29=0.
Look at 2%2Ax%2Bhighlight_red%28+-16+%29=0.
Removed extra sign in front of -16
It becomes 2%2Ax-highlight_green%28+16+%29=0.
Look at highlight_red%28+2%2Ax-16+%29=0.
Solved linear equation highlight_red%28+2%2Ax-16=0+%29 equivalent to 2*x-16 =0
It becomes highlight_green%28+0+%29=0.
Result: 0=0
This is an equation! Solutions: x=8.