Numerically two thermometers, one in Fahrenheit scale and another in Celsius scale shall read same at

To find the point where the two scales read the same, we set the temperature in Fahrenheit ($T_F$) equal to the temperature in Celsius ($T_C$) and use the conversion formula: $T_F = T_C$. Let this common temperature be $x$. The conversion formula from Celsius to Fahrenheit is $T_F = T_C \times \frac{9}{5} + 32$. Substituting $x$ for both $T_F$ and $T_C$: $x = x \times \frac{9}{5} + 32$. Solving for $x$: $x - \frac{9x}{5} = 32 \implies \frac{5x - 9x}{5} = 32 \implies \frac{-4x} {5} = 32 \implies -4x = 160 \implies x = \frac{160} {-4} = -40$. Thus, -40°C is equal to -40°F.