Question 1017979
<pre>{{{"10°"}}}{{{""<=""}}}{{{ C }}}{{{""<=""}}}{{{ "20°" }}}   

{{{"10°"}}}{{{""<=""}}}{{{(5/9)(F-"32°")}}}{{{""<=""}}}{{{"20°" }}}

Multiple all three sides by 9

{{{"90°"}}}{{{""<=""}}}{{{5(F-"32°")}}}{{{""<=""}}}{{{"180°"}}}

Distribute in the middle:

{{{"90°"}}}{{{""<=""}}}{{{5F-"160°"}}}{{{""<=""}}}{{{"180°"}}}

Add 160 to all three sides

{{{"250°"}}}{{{""<=""}}}{{{5F}}}{{{""<=""}}}{{{"340°"}}}

Divide all three sides by 5

{{{"50°"}}}{{{""<=""}}}{{{F}}}{{{""<=""}}}{{{"68°"}}}

Edwin</pre>