Question

At what temperature, will both Celsius and Fahrenheit scales read the same value?

• A. 10
• B. 20
• C. 40
• D. -40

Answer 1

The correct option is D -40

Celcius and fahreheit scale are related as:
$F=\frac{9}{5}C+32$

Since both the scales now read the same,
$F=C$

Subsituting, we get:
$C=\frac{9}{5}C+32$
$\frac{4}{5}C=-32$
$C=-40$

$⟹-40{}^{\circ }C=-40{}^{\circ }F$