That is the idea of the Big Mac Index. You have one product, and would like to figure out what the “fair” exchange rate is based on the theory (application) of purchasing-power parity (PPP). The link to the economist above shows a computation for the relative over- / under- valuation:
A Big Mac costs £3.49 in Britain and US$5.65 in the United States. The ...
RUBUSD - how many RUB per USD
TRYUSD - how many TRY per USD
RUBTRY - how many RUB per TRY
RUBUSD/TRYUSD = RUBTRY
64.42/4.48 = 14.3795 which is less RUB per TRY compared to the direct RUBTRY quote.
Use your USD to get TRY - gives 4.48M
Use TRY to get RUB - gives 64.4672M
Use RUB to buy USD - gives ~ 1.000.732,692 USD
If you are unsure about the direction, you ...