In December, Sarah's website had 72,000 visitors. In December of the previous year it had 51,500 visitors.
Percentage increase = [tex] \frac{population(present) - popilation(last year)}{population(last year)} [/tex] * 100
Visitors in present year = 72000
Visitors in previous year = 51500
Increase in the number of visitors = 72000 - 51500 = 20500
Percentage increase = [tex] \frac{72000) - 51500}{51500} [/tex] * 100
= [tex] \frac{20500}{51500} * 100 [/tex]
= 39.80582 %
So the percent of increase in number of visitors = 39.8%