Cost $30 retail price $40 find the mark up rate

1. Calculate the markup amount:
\text{Markup} = \text{Retail Price} - \text{Cost}
\text{Markup} = 40 - 30 = 10

2. Calculate the markup rate using the formula:
\text{Markup Rate} = \left( \frac{\text{Markup}}{\text{Cost}} \right) \times 100\%
\text{Markup Rate} = \left( \frac{10}{30} \right) \times 100\%

3. Simplify the expression:
\text{Markup Rate} = \left( \frac{1}{3} \right) \times 100\% = 33.33\%

4. The mark-up rate is
33.33\%