A Tricky Problem for the Doctor is another one page story, and is the only one in either Adventures in Time and Space or Journey Through Time to feature Romana. Romana doesn't actually do anything though, and there is no picture of her so there is no way of telling if she is being played by Mary Tamm, Lalla Ward, or if they got somebody else in just like they have done with Jo, Sarah and Leela.
The Doctor, meanwhile, is wearing a suit and tie again. Perhaps there is a dress code on the planet Skarium?
This is a story about maths! The baddy tries to defeat the Doctor by proving that 1=2, which doesn't sound so bad to me since it would make counting to 2 easier, but the Doctor is too clever.
The Doctor smiled. It would take more than a simple trick like that to break down his super reasoning powers. But would you have been fooled?
Yes. I am a cat. Cats don't do maths. QED.