Answer:
Your average improved by 13 [tex]\frac{1}{3}[/tex] %.
Step-by-step explanation:
First set:
(75 + 85 + 90 + 90 + 100 + 75 + 80 + 100 + 90) ÷ 9 = 77 [tex]\frac{2}{9\\}[/tex] %
Second set:
(85 + 85 + 100 + 90 + 100 + 85 + 80 + 100 + 90) ÷ 9 = 90 [tex]\frac{5}{9}[/tex] %
Improvement:
90 [tex]\frac{5}{9}[/tex] % - 77 [tex]\frac{2}{9\\}[/tex] % = 13 [tex]\frac{1}{3}[/tex] %