Answer:
[tex]\boxed{ \frac{ 1}{ 2}x - 18}[/tex]
Step-by-step explanation:
x = fans at Friday's game
½x = half the fans at Friday's game
½x – 18 = 18 fewer than half the fans at Friday's game
[tex]\boxed{ \frac{ 1}{ 2}x - 18}[/tex] = fans at Saturday's game.