The formula to calculate the rent proportion (RP) is:
\[ RP = \frac{R}{GI} \]
Where:
Let's say the rent (R) is $1,200 and the gross income (GI) is $4,000. Using the formula:
\[ RP = \frac{1200}{4000} \]
We get:
\[ RP = 0.30 \]
So, the rent proportion is 0.30 or 30%.