Iliana's math grade increased from 65 to 86. Fiona's math grade increased from 70 to 80. What is the difference, rounded to the nearest whole number, between the approximate percent increases?

Iliana's math grade increased by 21 which is 32.31%. Fiona's math grade increased by 10 which is 14.29%. To obtain the difference between the percent increases, subtract 14.29 from 32.31. Thus, the difference in percent increases of their math grades is approximately 18%.

The answer is approximately 18%