The rate is the ratio and the unit rate is the rate when the denominator is 1.
$279 for 9 tickets.
=> rate = $279 / 9 tickets => unit rate = $ 31/ ticket
$18 for 6 volleyballs.
=> rate = $ 18 / 6 volleyballs => unit rate = $ 3 / volleyball
4 fouls in 20 minutes.
=> rate = 4 fouls / 20 minutes => unit rate = 0.2 fouls / minute
36 strikeouts in 54 innings.
=> rate = 36 strikeouts / 54 innings => unit rate = 0.67 strikeouts / inning