Answer
$C=0^{\mathrm{o}}, F=32^{\mathrm{o}}$
$C=100^{\mathrm{o}}, F=212^{\mathrm{o}}$
Work Step by Step
Without using any equation, we see from the picture that when
$Celsius=C=0^{\mathrm{o}}, Fahrenheit=F=32^{\mathrm{o}}$
And when $C=100^{\mathrm{o}}, F=212^{\mathrm{o}}$.
(The second fact is not visible in the picture, but can be looked up on another thermometer.)