Nancy’s parents gave her $200 to start her savings account. After 5 months of saving, Nancy has $350 in her account. What is the rate of change of the amount of money in her account each month?
She had $200 to begin with, and now 5 months later she has $350
Subtract: $350 - $200 = $150
Divide $150 / 5 months = $30 per month