Question

At which temperature is the reading of the Fahrenheit scale equal to the Celsius scale?

• A. ${100}^{\circ }$
• B. None of the above
• C. $-{40}^{\circ }$
• D. ${40}^{\circ }$

Answer 1

The correct option is C $-{40}^{\circ }$

$C/5=(F-32)/9$
If we put $F=C=x$, we get,
$x/5=(x-32)/9$
$9x=5x-160$
$4x=-160$
$x=-160/4=-40$