To determine if the numbers 15, 45, 40, and 120 are in proportion, you can check whether the ratios of consecutive pairs are equal.
\[ \frac{15}{45} = \frac{1}{3} \]
\[ \frac{45}{40} = \frac{9}{8} \]
\[ \frac{40}{120} = \frac{1}{3} \]
The ratios are not all equal, so these numbers are not in proportion.
