Answer:
there was a decrease of 2.25%
Explanation:
Let me illustrate with an example
Assume the population is 100
percentage increase = 100 + 15 = 115% = 1.15%
Population after 15% increase = 100 x 1.15 = 115
Percentage decrease = 100 - 15 = 85% = 0.85
Population after 15% decreases 115 x 0.85 = 97.75
rate of increase = (97.75 / 100) - 1 = -2.25%