To find out how much you earn for washing 5 cars, first, determine how much you earn per car.
You earn $36 for washing 6 cars, so:
\[ \text{Earnings per car} = \frac{\text{Total Earnings}}{\text{Number of Cars}} = \frac{36}{6} = 6 \]
Now, multiply the earnings per car by the number of cars washed (5):
\[ \text{Earnings for 5 cars} = \text{Earnings per car} \times 5 = 6 \times 5 = 30 \]
Therefore, you earn $30 for washing 5 cars.