To find the % of nitrogen in the compound, must first find the formula mass of the compound through the following process.
Ca=40
N=14
O=16
Thus, formula mass= 40+ (14+16×3)×2
=40+ 124
=164
The mass of nitrogen in 1 mole of the compound= 14×2=28
thus to get the % of nitrogen we use the following expression
(28/164)×100%= 17.07%