Final answer:
The property manager earns $1,560 in one year.
Step-by-step explanation:
To calculate how much the property manager earns in one year, we need to find 10% of the gross rental income. Betty earns $15,600 per year in rental income, so we can calculate the property manager's earnings by multiplying $15,600 by 10% (or 0.10).
Property manager's earnings = $15,600 x 0.10 = $1,560
Therefore, the property manager earns $1,560 in one year.