Don't feel bad. It took me a long time to remember how to calculate ratios. I was really frustrated. Thankfully, Google was a big help.

Based on your CTx of 336 and P1NP of 37, your ratio is 10:1.1. This is a great ratio for maintaining bone health. Many factors influence bone turnover, so it's hard to say why your numbers were good on that particular day. Considering you have osteoporosis, this hasn't always been the case. It could have been a one-time thing, so take these numbers as just a snapshot

Here's the calculation
CTx/P1NP = 10/x.
336/37 = 10/x
10 ÷ (336/37) = x
10/9.08 = 1.1
x = 1.1
Resulting ration 10 : 1.1