In order to find the final molarity, we need to first find the total number of moles of NO3- from each source, combine them, then divide by the total volume.

Finding moles of nitrates will be by dividing the masses by their appropriate molar masses...

54.3 grams of NaNO3 can be converted into moles of NaNO3 by dividing by 84.98 g/mol

0.64 moles of NaNO3 which translates into 0.64 moles of NO3- (since there is a 1:1 mole ratio)

43.5 grams of Ca(NO3)2 can be converted into moles of Ca(NO3)2 by dividing by 164.01 g/mol

0.265 moles of Ca(NO3)2 which translates into 0.53 moles of nitrate (since there are two nitrates for each Ca(NO3)2)

Total mole of nitrate = 0.53 + 0.64 = 1.17 moles of nitrate.

Total volume = 0.560 L

[NO3-] = 1.17 moles/0.560 L = 2.09 M NO3- soluiton