1. **State the problem:** We have 80 students attending revision lessons in History, Computing, or Geography on Saturday or Sunday. 2. **Given data:** - Total students on Saturday = 37 - Students attending History on Saturday = 12 3. **Find:** The probability that a randomly chosen student from Saturday attended History. 4. **Formula for probability:** $$\text{Probability} = \frac{\text{Number of favorable outcomes}}{\text{Total number of possible outcomes}}$$ 5. **Apply the formula:** $$\text{Probability} = \frac{12}{37}$$ 6. **Interpretation:** This means if you pick one student at random from those who attended on Saturday, the chance that this student attended History is $\frac{12}{37}$. **Final answer:** $$\boxed{\frac{12}{37}}$$