To calculate the percent efficiency, you can use the formula provided:
\[ \text{% Efficiency} = \left( \frac{\text{Actual MA}}{\text{Ideal MA}} \right) \times 100 \]
Substituting in the values:
\[ \text{Actual MA} = 10 \text{ J} \] \[ \text{Ideal MA} = 40 \text{ J} \]
Now calculate:
\[ \text{% Efficiency} = \left( \frac{10}{40} \right) \times 100 = 0.25 \times 100 = 25% \]
So, the percent efficiency is 25%.