Harris westminster interview

Hiii I got an invitation to the Harris westminster interview on maths. Does anyone have experience on the type of questions they will ask, or the level of questions you have to solve?
And what if I don't know how to solve that question what should I do?

Hiii, I’m doing an English interview but one of my friends did a maths interview last year — and he basically said it shouldn’t be too hard, and they care more about your process and thinking than you actually getting it right.
Make sure you have a topic you really enjoy for maths and talk about it at the start.