Answer with Step-by-step explanation:
Percentage increase in score is calculated by the formula:

Iliana’s math grade increased from 65 to 86.
Percentage increase in Iliana's score is:

=

=32.31%
Fiona’s math grade increased from 70 to 80.
Percentage increase in Fiona's score is:

=

=14.28%
Difference between percentage increases=32.31%-14.28%
= 18.03%
Hence, difference, rounded to the nearest whole number, between the approximate percent increases is:
18%