#### Answer

(Isotopic Mass of N-14)(Abundance of N-14) + (Isotopic Mass of N-15) (Abundance of N-15) = Atomic Mass of Nitrogen
Suppose x = Abundance of N-14
This implies that Abundance of N-15 = 1-x
Therefore
(14.0031)(x) + (15.0001)(1-x) = 14.0067
14.0031x + 15.0001 – 15.0001x = 14.0067
-0.997x = -0.9934
x = 0.996
1 – x = 1 – 0.996
= 0.0036
Abundance of N-14 = 99.6 %
Abundance of N-15 = 0.4 %

#### Work Step by Step

As given in answer