Another chemistry question i’m not good at this at all:( has me stressed

Average atomic mass = 15.86 amu.

Explanation:

Given data:

Number of atoms of Z-16.000 amu = 205

Number of atoms of Z-14.000 amu = 15

Average atomic mass  = ?

Solution:

Total number of atoms = 205 + 15 = 220

Percentage of Z-16.000 = 205/220 ×100 = 93.18%

Percentage of Z-14.000 = 15/220 ×100 = 6.82 %

Average atomic mass  = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass)  / 100

Average atomic mass  = (93.18×16.000)+(6.82×14.000) /100

Average atomic mass =  1490.88 + 95.48 / 100

Average atomic mass =  1586.36 / 100

Average atomic mass = 15.86 amu.