This problem is giving information about a nylon polymer whose molar mass is 15,000 amu (atomic mass units).
The first subject of matter here, is to recall the monomeric molecular formula of nylon which is C₁₂H₂₂N₂O₂, and the definition of monomer (basic molecule able to react and form a polymer) and polymer (assembling of monomers).
Next, we calculate the molar mass of the monomer of nylon:

Finally, the number of units is calculated by dividing the molar mass of the polymer and the monomers:

Which is about 66 monomers.
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