Physics: Principles with Applications (7th Edition)

$1 C^{\circ}$ is $\frac{9}{5}$ times larger than $1 F^{\circ}$.
There are $100 C^{\circ}$ between the freezing and boiling points of water. There are $\frac{9}{5}$ times as many Fahrenheit degrees, or $180 F^{\circ}$, between the same two temperatures. The Celsius degree is larger.