The hostess is paid $50 plus 10% of the waitstaff's tips for each night she works. If y represents her pay each night and x represents the waitstaff's tips, then the equation that models this relationship is:
y = 0.1x + 50
This equation shows that the hostess' pay (y) is equal to 10% of the waitstaff's tips (0.1x), plus a fixed amount of $50.