How do i answer a problem solving question if I don't know where to start?

This is a very common question as many people tend to not know here to begin in regards to answering most problem solving questions generally. My advice would be to approach the question the way i would; begin with what you know. Rewrite important information from the question, this tends to help narrow down what you will need to work out (sub working out) before being able to work out what the question is asking of you.