Hello. your tables have a design issue and then the formula will be much easy.
you need to have a key between them all, which is not the case, since in the % you have them as 1A, while in the others it is 1
also, in Room, you have the value per person already at 8K, while in the example you said 7K
unify the primary keys (in this example i am assuming 1 and not 1A, and you can add the % and room in the same table based on what you're explaining - also having a better naming of the fields can help you
then, to solve your problem, bring the relevant fields into the main table (with linked records)
then the formula goes:
{Room price (from %)}/{nr of people}+{Minimum (from pp)}