Na = 43.4%
C = 11.3
O = 43.3%
Number of moles of respective elements is-
Na = 43.4/23 = 1.88
C = 11.3/12 = 0.94
O = 43.3/16 = 2.71
Simple ratio of moles is
Na = 1.88/0.94 = 2
C = 0.94/0.94 = 1
O = 2.71/0.94 = 2.87 ~ 3
Empirical formula = Na2CO3