Hello! I was in a similar position when choosing my a levels as I wasn't allowed to take both maths and history, I ended up choosing maths, which although it's sad that I didn't do history, I never regretted it. Saying that, it's always better to go with what you enjoy, maths is a very hard subject to do at uni and it's quite different to a level/higher, so if you feel you would regret not doing archaeology then go for archeology. However if you're really not sure and it's a 50/50 split then I'd probably suggest going for maths, better degree to have behind you, people assume you're really smart, better job opportunists etc etc