Andre has $30, and Erin has $14. Andre is saving $5 per day, and Erin is saving $9 per day. After how many days will Andre and Erin have the same amount of money?

Let x be the number of days it takes for Andre and Erin to have the same amount of money.

After x days, Andre will have saved 5x dollars and Erin will have saved 9x dollars.
5x = 9x-16.
4x = 16.
x = <<4=4>>4. Answer: \boxed{4}.