I need a formula to solve for how much sodium bicarbonate would be in a mixture of sodium carbonate and sodium bicarbonate.

Hi! I need a formula to solve for how much sodium bicarbonate would be in a mixture of sodium carbonate and sodium bicarbonate. This formula would need to be in the format of that I used a crucible to contribute to the decomposition of the sodium bicarbonate. So the amount of CO2 and H2O that escaped would have to be factored in.