Answer:
The answer to your question is: 20 hours.
Explanation:
Data
Hortencia = $350
Alex $18 / h
# hours Alex must paint to make more money than Hortencia = ?
Process
Equation 18 x n > 350
n > 350 / 18
n > 19.4 hours
If Alex work 19.4 hours, he will make the same amount of money than Hortencia, then He needs to work 20 hours.