Savanna had 40 iris blooms last year. this year she had 15% more iris blooms. how many more iris blooms did savanna have this year?

To solve this problem what you can do is the following rule of three:
 40 iris blooms > 100%
 x iris blooms > 115%
 Clearing the value of x we have:
 x = (115/100) * (40)
 x = 46
 Then, comparing with last year we have:
 40-46 = 6
  
 Savanna had this year 6 more iris blooms than last year.