There are four numbers to compare, salary_SF, salary_GR, living_cost_SF, living_cost_GR, and two obvious ratios you could take. You chose to divide salary/living_cost for each, but you could also divide salary_SF/salary_GR for ratio_1 and living_cost_SF/living_cost_GR for ratio_2.

So, you might find that it's a 50% lower salary, and an 80% lower living cost. That would be informative.