Question

At what temperature do the Celsius and Fahrenheit reading have the same numerical value ?

Answer 1

From the relation

$T_F=\frac{9}{5}{T}_C+32$

For the two to be equal,

$T_F=\frac{9}{5}{T}_F+32$

$-\frac{4}{5}{T}_F=32$

$T_F={-40}^{o}F=T_C={-40}^{o}C$

Answer is ${-40}^{o}C$