+ a question regarding amcs

for example, on the most recent test

one part of the question was to find the ratio of this geometric sequence - emphasis on RATIO (singular)
the answer was two ratios...plural

now for amcs
since next year would be my last year taking amc 10s, should I take both 10a and 10b for the minuscule (~0) chance of jmo qual or take 10a + 12b or 12a + 10b because amc 12s has lower aime qual lines?

also any tips for improving your aime score to ~7-8? I feel stuck in the 4-6 range