Answer:
400%
Step-by-step explanation
Given the following
Sales in the first month = $60
Sales in the second month = $300
Increment = $300 - $60
Increment = $240
Percent increase in sales = Increment/sales in the first month * 100
Percent increase in sales = 240/60 * 100
Percent increase in sales = 4 * 100
Percent increase in sales = 400%
Hence the percentage increase in sales is 400%